I've never heard the "Puhtrayon" one, so it must have been a long time ago.For literally almost a year he called Patreon "Puhtrayon" and still doesn't know how to pronounce "Buttigieg" (Booty-judge) or "Klobuchar" (Klo-boo-sharr), so it isn't even reserved for "scholarly" words (though there's plenty of that too). There's only so much you can use your barely-existent accent as an excuse for.
Regarding Pete Buttigieg, when Styx first started talking about Buttigieg, he was saying "butty-geeg (hard Gs)" and iirc he got flak for it, so he started calling Pete "Booty Judge" to "troll grammar nazis" and to belittle the man, whom he doesn't like.
His only problem with Klobuchar's name is, as you note, that he tends to sound out the U "oo" instead of "uh", which isn't that bad. You'd think he'd have corrected it by now, sure, but he's not butchering it.