We traded a low round pick (a 5th) and got said FB and a 6th round pick back. We didn't actually lose a draft pick, just a little bit of value on the pick in the trade. So yeah, I'd have no problem with something like that. Late round picks are largely fungible and part luck anyway.
The reality here is that you are trying to make the acquisition of a FB something that is really tough to justify what is a peculiar deal when in reality, getting a FB to play the limited snaps we use him for really wouldn't be that hard.
It's tough for you to justify. I can do it fairly easily.
1) Dallas plays a fullback even if it is sparingly.
2) Dallas likes for its fullback to be a core special-teammer.
3) Olawale is a proven starter.
4) The vet minimum for his number of years in the league is $915,000. (This includes players who are strictly backups/special-teammers.)
5) To secure the position for three years, the Cowboys paid twice the vet minimum with some of the money guaranteed.
It's silly to think just because he plays a limited number of snaps that you don't have to pay him to do it. It's either that or pick another competent fullback on the list and do the same.
If all of the other fullbacks considered to be in his class as a fullback (among the top four) get vet minimum deals for a similar number of years, then we can talk about it being a bad move.