Part of the point is to reduce the ketone and imine once it's produced. Okay, so you have Al2O3, this means that a rather vigorous reaction is going to occur, as Al2O3 converted to 2Al(OH)3 and that's one of the driving forces of the reaction as I understand it. Probably too fast. Just a thought, but how would you control that reflux? I guess A WHOLE LOT LESS Hg salt. What's wrong with Al foil?
BTW, I may be completely full of shit, but
Post 269032
(Osmium: "Re: Hg Amalgamation rates", Chemistry Discourse) is a great explanation of the reaction creating the reduction.
Who wants to play cops and dope fiends?