It is against the rules right now, but is generally not enforced, mostly because the verified system already exists, meaning that you couldn't impersonate the people Twitter had decided matter. It was also extremely rare for a blue checks to throw their verifications away for a stunt like that.

The incredibly harsh penalties for it (permaban without warning) are a new thing however, as is the whole "you lose your checkmark for a bit if you change your name", which is absolutely a reaction to him getting clowned on given how... problematic a decision it is, as name-changing is a very fun, common and often useful thing Twitter users do (artists frequently use it to indicate commission status), and adding this caveat reduces the value proposition of the subscription offer.