Most of the freak out I have seen I interpret as: “license says we can’t use it while competing with you but that has no real definition”

To me, it seems like an acceptable license, especially since development is happening on GitHub and they take PRs. Also the feature in the license where it reverts back to MPL after 4y is a nice security against the company doing anything else crazy restrictive - as you can plan on falling back to that version as a nuclear option.