Elected officials get security clearance by virtue of their election, and the president can legally classify or declassify information at will. That makes Trump’s security clearance fully legal, no matter his past. And I don’t think we want an alternative to that. If the America elects someone to be president, we don’t want to legally prevent them from doing the job.
The security clearance case I find most concerning is Jared Kushner’s. He wasn’t elected, messed up on his background check forms enough times that it doesn’t look like an accident, and couldn’t get a clearance through the normal channels. The president can reveal classified info to Kushner if he wants to, so it’s legal. But that doesn’t mean it’s good.