There's way too much money at stake here for this to be driven by grudges, emotions, or even reputations.

Benchmark's stake in Uber is worth $9.1b -- many, many times the size of their fund. They will do anything they can to protect this investment.

They very likely believe that the best way to protect their investment is to keep Travis out, and this is part of the process. Decisions like this aren't made at an individual partner level. The entire partnership decided to file this lawsuit, and that means it's a calculated decision.