What do you expect him to say and do? Resign because someone in another country got a job and you’re going to have to deal with them? This is what grownups do. They disagree and try to find common ground where possible even if it’s the thinnest strip of dirt, and you go from there. Where he went wrong was being super outspoken in the first place. Politicians should know better. As someone who will have to deal with foreign politicians all the time the last thing you do is slag them off, even if they’re in the opposition party and not actual currently in power.