Upon thinking it over, this is probably the best way for Trump to still get what he wants and make sure most of the onus for being an asshole who ground the government to a halt sticks to Pelosi and not himself.
Had this gone on too much longer, pretty sure both sides would have looked utterly unreasonable, while to this point Trump was able to mostly making Pelosi look like the jackass here (especially with that whole thing where he prevented her from that plane ride on the government dime), time was starting to run out unless Pelosi was gonna hand him another gaffe to make her look bad with, and he would have needed something worse than the last one.
Since he didn't have that, he picked the best alternative, which was to say he's all for the government reopening so people can get paid again, but the issue has not been laid to rest, and if she won't play ball in a few weeks, he's just gonna end run around her anyway lest the government grind to a halt again.
The whole point of this incident was to showcase how the Democrats are the utterly unreasonable assholes unwilling to compromise out of sheer spite, which was achieved. Dragging this out further negates any advantage in proving that.