The response that you're going to get is also my opinion: trades should be vetoed for one reason, and one reason only...if cheating/collusion is suspected. A trade should never be vetoed just because it looks lopsided on paper. So if you think these 2 guys are cheating...you should veto. Otherwise...let it pass. It sounds like you think they're cheating/colluding so veto would be the way to go. Good luck!
I agree with the first part, but I disagree on the count of doing it because HE thinks they are cheating. If an OVERWHELMING league sentiment agrees, then I think you would be within your rights to veto the trade. As things stand now, this is a supreme abuse of power and you should be keeping your hands off the deals. In all reality, LT has 1.5 good years left and Cotchery might be a big long-term target for this guy at the WR position. Just because you don't agree with a deal or see it as fair through your own personal lens, doesn't make it collusive. It is a bit uneven on paper, but there is nothing you can do IMO...
Also, I completely agree with the other guy about comfort in trading with other people. Some people are more open to trades and are willing to mix it up more than others. Scenarios (like covering bye weeks and injuries) come up all the time and trading is a great and viable way to solve those problems. If there are just 4 trades and nothing inherently crooked about them, then that is not a piece of evidence against these owners, it is simply a fact of the matter.
IMO, you should leave these guys alone an let them trade to "improve" their teams however they see fit - hope this helps