It's censorship and in this case it also makes for a defective product; meaning that they are willingly selling a defective product.
*Steam does this a lot; they will sell you a game that cannot run on your machine... but in their case, they have a client APP on the machine that can query the hardware and would conceivably allow them to provide a warning to the consumer prior to getting their money ~but they don't...
Take Bloodlines for instance... The game doesn't run on machines with 4GB ram or greater. Steam's official "Help" for me was instructions to cripple my RAM permanently via the boot.ini file.
(And yet it took 5 minutes to find a user patch to correct it. I had paid for it, and then had to resort to a suspect mystery patch to actually use what I'd paid for.)
I don't like Steam very much.