> i thought one of his tech decisions was bad (and in reality it was politically motivated to force people out.)

Let’s say you were right: It was a bad technical decision and it was politically motivated. What outcome can you expect from arguing with him on technical grounds? He knows what you’re saying is right, but he already knew that before making the decision. What you need to do is convince him not to act in bad faith. Try to figure out how to do that, and acknowledge if it’s not feasible.

Not to call you out in particular, but I see this as a common mistake by people arriving in a big company. Things are not as you wish, everything is too complicated, motivations are subtle and usually hidden. The trick is to get past frustration that reality does not match your mental model. (People aren’t being honest! How can I even work with people who don’t tell the truth!?) Abandon your mental model, acknowledge reality for what it is, choose goals that are achievable, choose actions that make progress toward your goals.