I don’t think that the tweet itself indicates he knew about these claims years ago:

“A sketch years later about a nonexistent man. A total con job, playing the Fake News Media for Fools (but they know it)!

Oops! This is awkward! @StormyDaniels’s Ex 😳#IDTheThug pic.twitter.com/GgLSxm2EJZ

— Deplorably🏴󠁧󠁢󠁳󠁣󠁴󠁿Scottish (@ShennaFoxMusic) April 18, 2018

…
5:08 AM - Apr 18, 2018”

Given the widespread publicity about her 60 Minutes interview, Trump could state that he first learned of this only a couple weeks ago. In any event, it’s certainly possible that Trump leaves all this up to his consigliere and asks not to be bothered about the details of individual cases. He could have issued a standing order to Cohen years earlier that any woman who is troublesome should be “warned” of dire consequences.