If you have time and the ebay listing is unclear, I would definitely ask. That way if they say you can unlock the boatloader and in reality you can't, you can return it to them as an item "not as described" at no cost.
Then I decided everyone who knows about bootloader unlocking would've already checked and mentioned if it was unlockable (but not if it wasn't, since why confuse normal buyers with a fringe thing), and I've never gotten a positive response trying to tell any seller about it, so I think I'm just wasting everyone's time.
Your mileage may vary.