I’m not going to comment on the “should they have” question, but I think this is effective as yet another piece of evidence that the Democrats are not just “persecuting” the opposition party. If sham trials are acceptable and possible, why not use them as much as possible?
Jokes can usually include a message, and often are more effective at delivering that message than a serious monologue with full citations.
Therefore, saying something is meant to be silly or a joke does not do anything to address whether the message behind that joke is a good one or not.