I'm old enough to have heard that song almost since it was new.

I'm not perfect at getting all lyrics correct from listening, but I'm also not bad. Never, until I heard the story only a couple years ago from ex-Skynyrd's, did I understand the line at about 1:44 to be "Boo! Boo! Boo!" I ALWAYS heard it as "Boo hoo hoo" or "Boo Ooh Ooh" or even "Ooh, ooh, ooh."

Unless someone has liner notes ("What are liner notes, uncle Jack?") shipped with an original pressing that state, "Boo boo boo" I'd say the odds are at best 50:50 that those were the original lyrics vs. historical revisionism from Skynyrd.