I think a lot of things about this war aren’t going to be forgotten, at least for a long time.Oh God Nance is a complete fool.
A long term issue will be this is the first time ever US personal (former or not or on leave) are openly stating they are killing Russians LL, that is never gonna be forgotten by huge segments of the population. And politically it's giving the Russian government a smoking gun figuratively and literally.
I agree that their presence is used to portray it as a Russian war vs NATO rather just Ukraine but even without their presence that bridge was kinda crossed with supply of arms anyway.
Also US citizens are free to travel and join in fighting for other countries even if the US itself is not involved in the conflict (Battle of Britain Billy Fiske for example). Short of designating the Ukrainian military as a terrorist organization (like ISIS ) I’m not sure how their presence could have been avoided.