He won't, because it comes with political repercussions, but what he should do is to call things by their names: that this is a bloody massacre, an extermination campaign conducted by Israel with the blessing and sponsorship of the US, while the whole fucking rest of the world was too coward to actually step in, so they looked away.
But instead of demanding accountability, he's washing away the blood and preparing to move on like nothing happened and nobody is to blame. It's disgusting, revolting. The tweet reply is right, Obama is probably one of the biggest disappointments of the generation.
I can't believe they gave the guy a peace Nobel prize, they should take it back.
Edit: you genuinely couldn't think of why people would be mad at Obama? And if you're not one of these "critics" yourself, then where do you stand? Because it sounds like you're sitting on the fence so hard that you have barbed wire shoved up your ass.
You could make it shorter: "Bernie Sanders is right."
This will also save a lot of work on a broad range of topics.