Satine Kryze did not unite Mandalore.
The Mandalorians splintered into different factions to oppose the pacifistic New Mandalorians during the Mandalorian Civil Wars, since the pacifistic ideology embraced by the group was an attempt to erase their heritage: the honorable warrior ethos (the Resol’nare) that had been the cornerstone of Mandalorian culture for centuries. Satine became the leader of the New Mandalorians, likely due to belonging to a family her faction regarded as nobility.
Eventually, the Mandalorian Civil Wars escalated to the point that the Republic Senate felt it had to intervene. The Jedi Council fell under the authority of the Republic’s Judicial Department, meaning that the Jedi Council sending a team of Jedi (Qui-Gon and Obi-Wan) to protect Satine was, in effect, the Republic deciding which faction’s victory would be most favorable to the Republic. It wasn’t an attempt at mediating a solution for the warring groups; it was an endorsement of a future regime.
The alleged ‘peace’ that’s portrayed during the Clone Wars only exists because the Republic intervened on Satine’s behalf (via Qui-Gon and Obi-Wan), and thus promoted a New Mandalorian victory which resulted in True Mandalorians and Death Watch alike being exiled from the planet entirely. Satine didn’t unify anything. She took a position of authority over a wartorn planet whose core population of survivors was comprised of people that already agreed with her.
Because this is relevant again: it’s necessary to add that it is completely impossible to exile a people from their homeworld ““peacefully””. The New Mandalorians removed both the Old (True) Mandalorians and the Death Watch from Mandalore following the end of the civil war. They were indiscriminate; if the warriors did not agree to follow the ways of the New Mandalorians (which by their very definition sought to erase the culture of the Old Mandalorians), then they were forbidden from residing on, visiting, or otherwise maintaining a connection to Mandalore. They weren’t asked. They weren’t politely shuttled away. They were forcibly relocated. That’s not benevolent. That’s not peaceful. That’s incredibly violent.
Satine Kryze was, at the very least, complicit in that exile. Demonstrating compassion to a dying man does not absolve her of that guilt or indemnify her from the consequences. No, we are not told that she, specifically, issued the mandate, or that she was personally responsible for carrying it out, but we do know that she did nothing to reverse it upon taking the throne, and she never stated that the exile was wrong. She maintained that Mandalore was to be pacifistic, and her acknowledgment of the Old Mandalorians or their culture and beliefs was framed to imply that they all stood under the same banner (Death Watch). The Old Mandalorians are never mentioned as a distinct group, though in Rebels we later find out that Fenn Rau exists, and can by his role (Mandalorian Protector) be presumed to be one of them. He trained clones on Kamino, and later fought for the Republic on Mygeeto. There is no canonical evidence to indicate he accepted Satine as being a legitimate ruler, only that he believed Bo-Katan was the best-suited among them to wield the darksaber and unite Mandalore - perhaps because, regardless of her previous allegiance to Death Watch, she was the person most well known for opposing Satine’s ideology, and because, in the course of so doing, she also very publicly split from Maul’s Death Watch faction.
Satine facing no mass opposition to her rule on Mandalore, again, is because everyone who disagreed with her had been forcibly removed from the planet. Death Watch was on Concord Dawn. Old Mandalorians, like Fenn Rau, presumably scattered across the stars to continue to uphold and honor the Resol’nare elsewhere. Being Mandalorian, after all, is not about being from a particular place or in a particular lineage; it is about swearing to an honorable creed, and then spending your life upholding it in everything you do. Terrorism is not honorable; therefore, if Pre Vizsla had approached an Old Mandalorian and requested their help to ““restore Mandalore””, their agreement would be contingent upon the strength of their personal dedication to and individual interpretation of the creed. It’s possible, and indeed very likely, that some former Old Mandalorians (such as the Wrens, perhaps?) shifted to support Death Watch because they felt as if the other Old Mandalorians would never organize a unified opposition to the New Mandalorians.
Summarily: Satine is, at best, a woman who lived through a civil war as a teenager, formulated a very desperate and impractical ideology to cope with it, carried that ideology with her when she took the throne, stood passive and unaware while her administration committed a cultural genocide, and then maintained a deafening silence after the fact.
At worst, she was the primary instigator.
Sources: STAR WARS: THE ESSENTIAL GUIDE TO WARFARE & STAR WARS: AGE OF REBELLION
