Its not the TV cut, I’ve always noticed it in that scene. I think the reason is simple. That exact bit, with lifting the arm, was an effects shot and was filmed months after principle photography. It’s probably not the same set and definitely not Richard Dreyfuss lifting the arm. Consequently Dreyfuss’ line was looped (i.e. recorded & added in later). And in this case, added in rather badly (this was the 70s). The acoustics of the added line’s audio don’t match the rest of the scene at all.
I haven’t scene a recent DVD of it, it may have been cleaned up. But it was definitely funky in the original print.