Well, maybe you could use a plugin on member_complete hook and do a str_replace of the javascript call. There may be a better way to handle it but I don't remember offhand how tabs are added to the profile.
I guess I should have let someone else help you...
ETA: On my test site there's one custom tab (added by a modification), and it's got it's own template. In that case it would be easy because the javascript "toggle_collapse" call is in the template code. If you know what GMap method would refresh the map, you could try putting it in there after the toggle_collapse();