He lied to Congress under oath at lteast twice: when he testified that the government wasn’t collecting information on American citizens and when he testified that the dossier had nothing to do with the Carter Page FISA application.
He admits to voting Communist for president once. How many more times is he NOT admitting to?
He has revealed classified information in tweets and other public fora.
All of those are good reasons to take his clearance.
He is a lucky Dude, so far. I some countries he would receive a bullet or a skin prick, from a radioactive substance and would be gone.