I lived in the next county over until I was 10. Not exactly a hotbed of Islam, or much of anything else. It's not impossible that it was done by actual Muslims, but it's at least as likely to be someone like a White Power asswipe trying to stir up shit.
When some incident like this occurs that affect a Dem constituency (Nooses, anti-fudgepacker signs on their door, etc.) it usually turns out to be shit-stirring from the victim his/herself or from the alleged victim group itself. The Left doesn't have an exclusive supply of idiots, I'll withhold judgment until they actually ID a perp.