I'm still a little dubious about Michael being able to cross over on his own - I kinda see Holy Places actually being more of a bastion against the Never Never. I'd say that unless the barrier is thin enough for anyone (including completely vanilla mortals) to cross over then it should require at least Thaumaturgy to do so (or Ritual if the area of expertise is to do with transportation and world-walking).
I guess this is one of those areas where we'll have to agree to disagree.
If Michael Carpenter wanted to cross over into the Nevernever, I would make it rather difficult for him to do so. He calls up Harry, he does the research on his own, or he looks for a place the barrier is really thin. If Michael, Knight of the Cross and Fist of God, needs to cross over into the Nevernever to pursue a fleeing demon and save an innocent soul, I can't see anything being capable of barring his passage.
That's the difference to me -- one is a character looking to pass over for some reason. The other is a high-concept driven Emissary of Power smashing through the barrier between worlds because it furthers his patron's designs.
I'm kind of a story guy anyway. If a player makes a case for passing over because it fits his High Concept, I'm not going to sweat it over whether or not he has a specific power... unless the story is enhanced further by his being barred from the Nevernever for some reason.
I think it makes a lot of sense for Focused Practitioners and other members of the supernatural community being able to pass over where the area fits with their personality or concept. It's not like all White Court Vampires have Thaumaturgy or Ritual, after all, and they're the specific example for supernaturals being able to cross over where it resonates with their concept...