Update: The way the bolt fell, it is lodged behind the starter cross ways with the flange just at the bottom back of the starter so that is what is preventing the starter from being pulled back out. I don't think that even opening things up from the top will make it possible to dislodge the bolt or the starter. From looking at it with an endoscope camera, it looks like the starter is flush against the bell housing. So our options are to get another mounting bolt and bolt that in and just leave the stuck bolt and hope that the starter IS properly mounted straight in the bell housing or get a long narrow hacksaw and cut the stuck bolt which should free the starter to be pulled back out of the bell housing and the bolt to be removed. The mechanic had the starter in the bell housing with the front mounting bolt snugged when he dropped the back bolt so it should be in there straight. Either way, we have to get another mounting bolt.
The original problem was he "snugged" the first bolt until starter didn't move. What does that mean? Unless both bolts are started the starter holes are aligned so when he went to start hard to get to bolt it didn't have a complete hole and he dropped it. This is just my observation.