That's dancing awfully close to collusion. Hasselbeck has been hurt/out, so the guy can make the argument that he's taking a risk that Hass will be fine when he comes back, but that risk is pretty minimal.
I think, much as I hate the veto, this is one I would consider. But, if you want my honest opinion, this event in a vacuum doesn't warrant a veto. It's a lopsided trade, but unless these two guys have a history of questionable practices I think it's not enough to veto the trade.
You're going to lose a league member over this. If this guy has been a decent owner over the years I'd say it's not worth losing him for this one deal. If he's been a pain in the backside for a while and has made other questionable deals, maybe he should just go, but if that's not the case I think vetoing a questionable trade is a bit much.
How 'bout them Huskers!