See, This is the reason why iskcon is established. They want you to believe that all gods are slave of shree krishna and shree krishna alone is supreme god. read more
So even if Iskcon folks are insulting Lord Shiva they are indirectly insulting Lord Vishnu/Rama/Krishna. Believe this is just their wrong way of marketing Krishna culture whereas Krishna himself is a devotee of Lord Shiva-if they are doing so or telling these things to people around. read more
If ISKCON is thinking that they are actually insulting Lord Shiva by calling him a demigod, then they are a bunch of morons. Those who think Lord Shiva is actually getting insulted when ISKCON calls Him a demigod, are a bunch of uber morons. read more
Lord Siva is there as protector of the dham / temple site. read more