Veto when you sense someone tanking?

So one of my league mates has had one win for the last three weeks. He still has 1 win. A few weeks ago, he traded DJ for Doug Martin & Austin Ekeler. (Days earlier he declined my Coleman & Howard for DJ trade??)

He is obviously tanking and just selling all his assets. This is a redraft league. Do you guys think it is every right to veto the trade late in October when you know someone is tanking ?