They want to muddy the waters by arguing the FTC is impartial towards Amazon. But the problem with that argument is that it's not the job of the FTC to be impartial. Their mandate is to protect competition and consumers, which is naturally impartial to individual companies.

I think you meant the opposite of impartial towards, i.e. biased against.

It's like the GOP currently trying to impeach a newly-elected judge in Wisconsin because she previously described the state's maps as gerrymandered, ergo she will not be able to rule fairly on the matter when it comes before the court. Obviously both examples are cynical and disingenuous, since the implication is that the only person qualified to do a job "fairly" is someone who has never thought about the relevant subject matter at any point in time.