The idea behind the "good cop" delusion seems to run along these lines: If you are robbed by a gentlemanly robber, you weren't really robbed.
And yes, most cops have behaved nicely toward me, even while they robbed me. (Although they have all acted scared while committing their act of enforcement.) Does this excuse the theft? No. That's ridiculous.
A polite archator is still an archator, and is not a "good" person. Ever. Not even if you approve of what they do.