Levandowski had done a lot of valuable stuff for google before, so they kind of gave him free reign even though he was known for not being easy to deal with.
Free rein*. The analogy is to horses, not to kingdoms, although I have heard that the one can be exchanged for the other.
sorry and thanks for correcting, not a native speaker.
I've seen native speakers do worse. :) That one is especially tricky because the meanings of the two words are actually kind of related, to the extent that "free reign" makes a kind of sense with nearly the same meaning, despite not being the original idiom.