Hi, Dunn. I think you’re wrong about this. There is no higher chance of revoking than with digital codes. Gifts are often obtained with regular Steam vouchers for games someone doesn’t want, but this way can get them for cheap. Then you buy it as a gift and there is no chance for that game to be revoked. Even some of regularly activated games give you another copy as a Steam gift. Or is there something I’m not aware of?
For games to be revoked on Steam you need to obtain them using stolen credit card or by opening dispute on PayPal after transaction is completed (maybe there are more ways I didn’t hear of). It doesn’t matter if it is a Steam gift bought on Steam, or Steam key bought somewhere else (legit stores). Actually, if you’re obtaining digital codes from other reselling sites like G2A/Kinguin (like delayed delivery sellers do), or by abusing HumbleBundle referral system, there is also a chance for games activated by digital code to be revoked.
I’m selling keys only, but have few games sitting in my Steam inventory that are 100% legit. I got them by farming trading cards on Steam to get cool discount vouchers for those games later. I keep them as birthday presents for my friends, but I don’t see any reason for them not to be sold here through coordinated transfer.
At the end, if it’s not against TOS, it should be good as long as buyer gets what he payed for.