But it’s not exactly a threat is it? It’s a very reasonable observation about how Ukrainian refugees might feel and behave.
Wouldn’t you feel the same way? Your country gets invaded, you flee to a generous supporting friendly country. That country stops being supporting, and your chances to return home start to vanish. You didn’t choose to be here. Now you’re stuck in a foreign country that you feel could be doing more to fight injustice and give you a chance to return home.
He’s the president of a democracy, not a mind controller. People will feel a certain way. He’s simply observing this potential situation, as a warning to the allies not to slide into complacency.