This comment and others like it are wild to me.
Since when was the default to assume malicious activity and victimization, and then to ask for proof otherwise? Obviously we should do the reverse. There should be evidence of theft rather than assuming theft as the baseline.
For starters, if the band's handles were taken non-consensually, then the least we should expect is a public complaint from said band.
This is doubly true in a world where social media handles are routinely bought, sold, and traded. And triply true where the supposed victim of this crime is an incredibly popular group of people with an extremely massive platform, and it's 99.9999% likely that Meta knew this going in.