As I understand subsidized vs. unsubsidized, yes it is. I can buy the phone without entering into a contract. I can terminate service with VM after 30 days. I can sell the phone to someone else who can choose to buy service from VM or not.
True it isn't unlocked, but I'm not aware of anyone saying unsubsidized == unlocked.
It is worth splitting hairs because AT&T and Verizon are guaranteed to either make $75+/mo (it was $110 for my minimal minutes plan) for 2+ years OR a $200+ cancellation fee to make up for the cost of the phone.
You can buy a Virgin mobile phone and never activate it. You can stop paying without penalty after your first month. That's unsubsidised.
OTOH, Virgin USA may still be subsidizing it (by charging below cost), and just willing to take a loss if you never activate it. Since it only works on the Virgin network anyways, this isn't a risky gamble.