Of course we sanction citizens and former officials, but when we really want to send a message to a government, we sanction current officials. Instead, China and the rest of the non-Russian world treated the last 4 years as if that regime wasn't long for the world. They waited it out.
And it is an ousted regime. Any regime that leaves power against their will is ousted. The way in which they are ousted isn't all that relevant. The fact that Trump's foreign policy, if you can call it that, ran counter to nearly every other US administration (or regime) makes it an easy game for China and others to play. When dealing with Trump, they were dealing with Trump and not the US because Trump was a 4 year blip in policy continuity. And that was always the problem with Trump. He completely abandoned continuity. No other modern President has done so even when they may have desired a different approach because the "word" of the US matters. Other countries are clearly ready to let us get a do over. We should take it. There is simply no point in defending Trump policies that ran counter to decades of US policy.
And don't pretend for a second that this is about the Uighurs. Doing so is simply disingenuous. Its a trade war move. Pompeo gives less of a fuck about the Uighurs than China does. If we want to make moves based on civil rights, and we should, we should not concern ourselves with sanctions against Pompeo in doing so. Apply sanctions to them until they leave the Uighurs alone. They can keep the sanctions on Pompeo all they want.