If don't return to SGS / talk to Tanner anymore after completing initial quests and return to his office after visiting Deep Caverns, Gorsky will still be present here. However, he will not come to the meeting room if assemble the council. If talk to him, he'll have a chat with "Unknown" (Tanner), this will activate "Assist rail crossing" (impossible to complete) and "Meet Gorsky in Core City" quests.
I think he just should leave for Core City and ask any council member to invite you there after you returned from Deep caverns.
