Not really Trump-specific is it, given Europe seized a ton of Russian assets. Maybe they just realized how easy that was and that nobody is going to war over it.
But we live in a world where it is considered poor form to expect history qualifications in elected office, so this kind of crash, followed by the long descent, is baked in.
One, Russia’s stuff hasn’t been seized. Europe tried. But, in true form, failed to get its act together.
Two, is the argument really that Trump would be constrained by precedent if Europe and the U.S. got into a situation where seizing the former’s gold comes on the table?
They were only insured up to something like 100kEuro, and it was values above that amount that got "bailed in" when the banks failed.
It sounds optimistic, but after Stalin came Khruschev, a much more "normal" person. Though it is true he didn't last even a decade. But there was a lot of political thaw in between, and some of this thaw survived.
It is quite obvious that Russia miscalculated heavily, and someone who wasn't part of the small team that decided to go in, and thus whose face is not at stake, may be more amenable to declaring "OK, our goals have been basically met, let us solve the rest at the negotiation table".
From what I get out of my Russian and Russia-located acquaintances, people are growing tired of this nonsense. Not yet rebellious (though some of the recent actions of the government, like messing with the civilian Internet to the point of unusability, plus mass culling of cows in Siberia, have certainly increased the total level of anger), but dead tired. There is political space to conclude this war, and the reason why it isn't happening is personal.
Those assets are frozen, not seized.
Confiscation would be e.g. definitively taking control and disposing of it, the proceeds going in to the general funds of the relevant country.