If you write a firmly worded letter to your Senator, you are protesting and it would take the most abusive stretch of discretion to consider it criminal in any way.
If you drive with your buddies in dark of night to a store and do a smash-and-grab, it would take an absurd ideological contortion to consider it protesting in any genuine way.
In real life, there's a spectrum moving from letter-writing and sign-holding into civil disobedience and then into forms of disorder.
If you start with the observation, as you have, that "people are taking this opportunity to steal and ... burn[] down shops," I would submit that you shouldn't then apply the term "protester" to what you are defining as an opportunistic criminal.
You know what has worked really well for Niketown in Seattle the last few days? They just have a bunch of beefy dudes in athletic wear (some Polynesian fella cheered them as being Samoans, I dunno, but it's relevant mainly in that they look not like a bussed-in white-only goon squad, and optics are gonna matter in this crisis) standing around it. Nobody's messing with those guys.
If your cops aren't up-armored and manning a barricade of people doing free speech stuff, they can, you know, take 911 calls and go respond to actual calls.
I would challenge your insinuation that theft and arson are "in places where the police [are] weak" and the implicit corollary that you should then make those police more "strong." I would grant you that (perhaps tautologically) those crimes happened in places where keeping the peace has been done poorly, and it should be done better.