Price controls could lead to shortages

Nope. That's just the line the profiteers feed the most gullible of their victims so they'll defend their corrupt practices.

which is reportedly common in Communist countries

You know what's also common in nominally communist countries?

Government corruption, wealth and power being concentrated in the hands of a few privileged people, and that privileged class tricking their victims into being their advocates.

Exactly like capitalism in general, and especially US capitalism.

which I'll concede to Trump

Well that's just stupid and unnecessary. It's not like he has a point or anything. he's just throwing buzzwords at the board and seeing if any sticks

why do Trump supporters—presumably a vast majority being consumers—support tariffs, quotas, and seem indifferent to IP ("intellectual property") trolls and their lobbies? Why do they oppose abortion (and perhaps contraceptives) when fewer children means less need to purchase stuff?

For the same reason that you think price controls lead to shortages and that any country calling itself communist is an accurate representative of what communism is: lots of internalized propaganda.

Disclaimer that shouldn't be necessary: I'm not a communist or in favor of communism. It's far too authoritarian, inflexible, and unprepared for when the real world doesn't correspond with theory.

Perhaps price controls for basics are needed

No "perhaps" about it. The profiteers have demonstrated that they will always raise prices when not forced not to, far beyond their customers' ability to survive in the long run. It's long past time to make social murder illegal.

but this is not the ideal

No, the ideal is that all companies are worker owned co-ops so that the socially good and the fiscally good are inseparable so that there's no systemic incentive to profiteering.

We're not getting there within any of our lifetimes, if ever, though, so let's focus on what is already possible and necessary: price controls.

if you support price controls because you favour socialism

Nah, I support price controls because they're necessary to reduce a pandemic of standardized plundering of the poor. Call it socialism or don't, just get that boot off my neck.

then again, Trump is kinda right here.

Nope. Not even kinda. He doesn't know what communism is any more than he knows what asylum is, how to prevent forest fires, or how to deal with hurricanes.

The man is a colossal idiot who happens to be tragically effective at self-promoting. He's also a fascist and the poster boy for malignant narcissism.

You do not, under any circumstances ever, have to concede ANYTHING to him as, even on the incredibly rare occasion that he's right about literally anything, he got there by accident.