A big problem with Biden's ability to crack down on dissent on this issue is that he has grudgingly tolerated much worse dissent from the party's left flank. What Coons and Fetterman are saying is nothing compared to Tlaib coming just short of chanting "Genocide Joe".
If Biden was smart he actively would get around 100 pro Israeli democrats in the House and 20 pro Israeli democrats to vote for a bill mandating aid be given out and then vote to override his veto too.
That's exactly what would happen if he pushed this too much further, I think. Obama was willing to pick this fight, while Biden has the next term to think about.