The question of lubricating machine tapers has been discussed in the machine taper world. See
http://www.practicalmachinist.com/vb...tapers-233868/ for a three post entry regarding why or why not to lubricate morse or other machine tapers.
Quick overview: tapers are generally lubricated lightly on even self locking machine tapers primarily to allow disengagement without galling after the work is done.
I'm not so sure I would be that generous. Maybe a small amount of WD40 or other light lubricant? Maybe for no other reason than to exclude water and prevent rust?
Although rust would "fix" the bond, wouldn't it? And make the taper even less likely to come apart? But that would make new brake pads more difficult too, of course.
Joe K