I think he is doing exactly what any middle of the road US politician would so - support Israel's right to defend itself while pressuring it to be cautious. The issue is Netanyahu is simply not responding to pressure but even with that most Americans still think we should completely support Israel.
Where President Biden and almost every other President has mis-stepped is not reigning in illegal settlements long before the events of October 7. Those settlements have long inflamed tensions in the region and the United States should have sanctioned Israel and American funders of them (hello the Adelsons) long ago. It also should have threatened to withhold security funds if they continued
The only President who even came close to trying to reign in the settlements was G HW Bush back in 1991
"Although the circumstances today are not identical, Bush’s showdown with Israel in 1991 over the terms of U.S. loan guarantees serves as an illustration of what a more evenhanded U.S. approach to the conflict could look like. Bush withheld the loan guarantees until he was satisfied that the money borrowed with U.S. assistance would not go toward Israeli settlements in the Palestinian territories.
“Bush established consequences for bad behavior, and he got results,” said James Zogby, president of the Arab American Institute. “It can happen again.” At the very least, progressives see Bush’s actions as a useful reminder that renegotiating U.S. aid to Israel is not an extreme, left-wing idea.