From doing a quick read on squid tentacles it sounds like they're pretty aggressive and get big. They'll also eat your fish and kill any coral they come in contact with. Doesn't sound like they move a lot and assuming the other nem doesn't move near it it should be fine with them. That being said if it were my tank I'd get rid of the STA and go with a more common species that has much more readily available care info, I'm also not a fan of things that can get big and kill everything in the tank. Just my $.02 though.