"What do you think is more significant, #2 or #3?"

Quite frankly, neither. Because Twitter political posters represent puny and unreliable voter bloc, and I don't imagine Yang to be someone to be bullied by his own staffers. That's the opposite of what a leader is. And like it or not, staffers come and go, but a Yang that created Humanity Forward nonprofit hasn't been duplicated, as far as I can tell.

"His very unquestioning and monochromatic stance on support of Israel goes way back, as one can see."

Unquestioning? In your linked video Yang actually emphasizes "there's a certain relationship with Israel that we need to strengthen", i.e. he questioned/examined and concluded that the status quo was the way to go (you disagreeing with the status quo is not the point, the point is Yang questioned it). And a monochromatic stance is to toss either party out of Israel because either party claims rights to the land, so a two-state proposal is therefore non-monochromatic.

Tl;dr: Once you kowtow to finicky, unreliable voters, you'll have to kowtow for the rest of your life. So I'm glad his follow-up did not change his original stance, and only unquestioning and monochromatic actors would extrapolate from his first tweet that he is anti-Palestinians.