Can they? I don't know, but I imagine that at this point, everyone still working for Twitter is there because they don't have any other realistic option.
Most people working there are looking for other jobs. It is not hard to find another job, but in this market it is hard to find one that pays the same. A lot of people have 4 year stock grants and annual refreshers, pushing their compensation very high which can only be matched at other tech companies, which currently are not hiring much.
That's assuming too much in my opinion. Not everyone has the same or similar opinions regarding their work or Elon, even if it's hard for you to believe.
It's harder with visas, because you're not gambling if you can find another job, you're gambling if your employer can acquire a visa in time for you to not be deported.
Right, so it's still justified to feel bad for visa workers in this case, because they are stuck at an abusive workplace because of circumstances of their visa.
With forced RTO and "hardcore" mandates, it's difficult to find 6+ hours of time to interview at other companies (assuming there are any open visa sponsorships available).
According to this one link [0], H1B "tranfers" are not subject to visa caps. Plus you can search for new jobs and start the process while still employed.