Personally I would only ask  him if you genuinely feel that you'd be okay wether he says yes or no.. they say only contact if you feel inspired.. like if it's done out of unconditional love.. if you feel you'll be disappointed if he says no then I wouldn't ask.. you've gotta be completely at peace within yourself first.. & not depend on the outcome.. if anything I would just visualize him being there.. & he might contact you & end up asking you if he can go ;)