I have no idea what caused him to change his stance otherwise.

I’m assuming the guy got some non-public info on how that ICJ case is doing and doesn’t think it ends well if you have to explain how no, actually, we don’t give a shit about the geopolitical order. I think that’d be a tough sell to lots of germans, you don’t really get the kind of jingoistic approaches like, say, the US or Britain that much, it’s much more along the lines of being “the only sane man” doing technocratic aid