The "Significant Saints" section on the official website confirms the Campbell Suite is named after Robert Campbell.
http://www.perthstjohnstonefc.co.uk/significant-saints
"What Robert Campbell would make of McDiarmid Park, the modern game and the communication medium that is the internet, we can only surmise. However, one thing is for sure – he, more than anyone, deserves his place in the history section of this website and he would no doubt be pleased that the Campbell Suite within the current stadium is named in his honour."