> I printed this out of carbon fiber ASA, but probably boring old PLA would have worked just fine.

I doubt it: PLA begins to soften at as low as 55 degrees Celsius. If there's weight on it, it's worse: the piece shall quickly deform and become unfit for its purpose.

This rig looks like it means business: I think PLA would fail.

If, like me, you cannot print ASA (say because you've got a printer that is not closed and that won't heat enough), then PETG-CF (PETG reinforced with some carbon fiber: it's got better heat deflection than plain PETG) is a safer bet than PLA for parts to put in PCs/servers/rack. Moreover PETG-CF do look really good.