I would say this is more of a security issue. If the protests had been peaceful, and had there been no deaths, I doubt this request would have ever been made.
The mob was the specific instrument in this instance. Mobs are used regularly for similar purposes.
IMO the question at hand is whether as soon as some group threatens violence the USA kowtow. This appears to be the case here - the USA administration intervening in the free speech of a citizen in order to further the aims of a group because that group has threatened (and acted) violently.
I would say this is more of a security issue. If the protests had been peaceful, and had there been no deaths, I doubt this request would have ever been made.