Bob, I don't know if you had a look at the picture I put a link to, but to me it looks pretty obvious that the air can only go up to the bleeder, even more if as you say, "the drillings into the brake slave are angled towards the center of the unit", no? With this set-up, "the centre of the unit" is still lower than the bleeder and the bleeder seat. Or I don't understand anything any more...
Well, I haven't tried to bleed the brake so far, so I can't say for sure, but I don't see where a bubble can be trapped inside the cylinder with this set-up