It comes down to the referee in a way. If Zemmama had been booked, which i feel he should have been along with Riordan, then he would have stoped goading the fans.
However, It is absolutely unnaceptable for anything to be thrown at a player or indeed onto the pitch. Zemmama's immediate reaction was to tell the fans to calm down instead of going balistic towards the referee which is a credit to the guy. An absolutely fine footballer and he tore us a new hole at times.
Still, the wee bugger could have caught the object which would have been an even more red neck to whoever threw it haha.