Conspiracy brain thinks of a few reasons:

1. To preemptively establish what "real crazy" looks like so that we tolerate what he's actually saying and doing more

2. To muddy the lines between fake and real so that everyone is too confused to fact check anything

3. Garden variety people being stupid and wanting to exaggerate something because exaggeration=funny, and they're not aware of the harm this does

4. To bait the left into accepting the same sort of "the fact that this is believable (to me) PROVES that this is valid possibility and worldview" mentality that the right adopted a decade ago, which ultimately makes people much easier to manipulate

5. To position the left as yet another entity that promotes its views via misleading "jokes" that on the one hand legitimately misinform people, but when called out can be defended as "just a joke that you were too stupid to recognize" - that is, borrowing another successful but evil strategy that the right has recently made use of