I think you did miss a joke, or at least didn't parse the sentence correctly (which probably negates his point in and of itself).

After a bit of clean up, it reads "If Yoda could make his point clear, nobody should give a shit about Oxford commas."

Ah! I was parsing it as something like "If Yoda could give a shit about Oxford commas, you shouldn't either." Which then lead to thinking it should have said 'couldn't' instead.

Cheers