While I think you may right about the status of BL, pubs or let's say tribute acts are filled with musicians that quite possibly can play circles around any current living rock legend, including the Maiden boys
The key difference here is - the pub/tribute guys are not famous and do not posses that star charisma, aura or whatever it is called, that thing that makes people consider musicians like Mikkey Dee for the vacant spot in Maiden.
Because he is famous. But it doesn't work that way, Steve does not care who is famous or who is not, he wants someone to do the job and be discreet. The second part is probably even more important than the musicianship itself.
So I would say the gig goes to Simon or Joe. Or even Bruno - in case Steve has let go of that only-british-policy with age.