I'd argue advocating for taxation isn't really threatening to his own class. He'd be a class traitor if he advocated for workers' democracy, better working rights, stronger unions, no exploitation of foreign workers, etc.

The issue isn't that taxes are too low for the rich (even though they are), the issue is that they exploit us (both domestically and internationally) and get richer from owning rather than working, and that anything that we do to challenge this arrangement can get us killed.