Would you all allow a trade where Team A trades to Team B b/c Team A wants to make Team B better so that Team B can take down Team C? Team B doesn't know of this motive and the trade is for fair-market value (when looking at previous trades in the league). The league doesn't vote on trades and the Commish rarely vetoes (might not even have that power per the league's rules).
On the one hand, Team B isn't aware, so it's tough to say it is collusion, and the trade is still for what the league has determined to be fair-market value, so while the deal may make B better in the short-run, it will give him some pain later on down the road. Plus, just because Team A says something, doesn't mean that it is necessarily true. It is hard to prove ill-motives.
But on the other hand, if Team A does say that to somebody and the Commish catches wind of the remarks, it can still come off as shady and a veto-worthy trade. It might make the Commish think he needs to step in to protect the integrity of the league.
The trade looks like this
Team A Receives: Mike Williams, 2019 First Round Pick (From Team 'B'), 2019 First Round Pick (From Team D), & Rashard Higgins
Team B Receives: Michael Thomas