Trump has been taking a great deal of heat over his rash announcement that the US would be pulling out of Syria very quickly. He's changed his tune and words.
Had he simply been throwing Erdogan a bone with the plan of rolling back his statements? Who knows?
Trump certainly has no affection for the democratic-socialists: the Democratic Union Party (PYD) of which the YPG is a militant aspect. However, he was probably surprised when met with so much hissing from not only the neocons and liberals but also progressives.
Progressives are typically much less militant, but the US could withdraw without leaving the SDF like ripe, low-hanging fruit for Erdogan to pick off.
Anyway, Assad has more reason to make a deal with the Kurds now because if he doesn't, the US will have more of an excuse for sticking around.