And it’s his right to find some flimsy, but legal, pretext to detain you when otherwise he wouldn’t have done. You don’t have freedom from the consequences of your speech.
Treat someone with respect, and you’ll get respect back 99% of the time. Treat them like a dick, and you’ll get dickishness back, unless the person you’re being a dick to is the better person.
You have nothing to gain, and plenty to lose, by being a dick to the wrong people. Don’t do it. It’s not only the wrong thing to do to disrespect a representative of a democratic government, but it’s fucking stupid to piss off someone with handcuff, weapons, and the right to use them on you.
And don’t try to tell me that if you’re in the situation of insulting a cop, you haven’t broken some minor law or other. You will have done, apart from anything else you’re disrupting police work.