I don't think the trade is vetoable, or even questionable. Both teams seem to gain something, Team A with more power and Team B with upgrade at pitching and saves. If you want to see a vetoable / questionable trade look at this trade I was able to get (The other owner proposed it and he did say he didn't like A-Rod / Yankees).
At this exact point in time, I'd say that the Webb side is definitely coming out ahead... I think I'd rather have Webb than Peavy at this very second (although HA no complaints for either). Hoffman has been a little bit of a liability on your ERA and WHIP, and the NL west IS much better on the whole this season, but he still has 4 saves even with all that so far, and you know he's gunna keep getting em, no matter what. The investment on Howard and Verlander can easily make the other guy a very happy owner in a week or two from now, so this trade is just a really good one for both imo.