I just met Grigor on Storm´s Reach with my 2nd character and he tells me to "Meet me inside the mine". I do not remember at all to have ever seen him IN the mine, only found evidence and then returned to him on the surface... Did I miss him anywhere in the mine?
I've been wondering that too (a cut plot element)? or possibly a typo or something. As far as I know... we will never find him IN the mine. We find some information that is useful to him in the mine, and then use to to finish that quest.
i think he's just being a coward: he just tells you he'll meet you inside so that he's not expected to go in with you right then. if he were actually willing to go in himself he'd already have done it.