No, no, no....
If they go into admin he loses control. However, as the only secured creditor (maybe) he would be at the forefront of the administrator's responsibilities. As for returning shares... it's a moot point. Someone will either buy the shares to get them out of admin, or someone will agree a deal with the creditors and buy the assets of the business in which case the shares become pointless anyway.
I agree with your final paragraph though!