My proposal actually uses the apathy of lazy lords against them. It means that if they don't want that temple there then they can raze it, arrest the priest, or more. It would encourage them to either care more about their region or let perhaps a religion that is more poisonous to them spread. It gives them choices instead of knowing that no matter what nothing can happen without their approval.
As I understand current BM code, Lords can not erect statues in estates they don't own. Perhaps this is going to be changed, but as it is it gives one example of how things can be built within a region without the Lord's direct approval.
I do understand how to be a pest to Lords, but with the limited player population it also means that resources tend to be focused more on state matters (which is logical for Lords) and not with something that doesn't give them a benefit or honors them or their direct chain of command. Since the building of a temple requires the Priest to go there, it means that there's also a risk you could be arrested for building the temple.
Also, current BM code has many things where the original builders have to maintain the things they build. For example, the fortifications are maintained and built by the same person. The current Priest code is the only example that I can think of in BM code where this isn't the case. Essentially, the Priest is responsible for maintaining something that someone else builds.
Then, consider this point as well. If I can preach in a lordless religion to expand the faith, why shouldn't I be able to build a temple to expand the faith. If anything a Lordless region means there is no "king of the region" to stop it. This will either force realms to deal with the issue by sending a force to tear it down, assigning a lord to go there and tear it down or letting it be.
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In summary, my proposal's benefits are that:
1) It expands the Priest role slightly in a logical way.
2) It helps the Priest use any money earned towards the faith. (Can't recruit troops)
3) It allows more RP opportunities (i.e. Grand Temple openings, fights between religions trying to build temples, Disgust by region lords, etc)
4) Relieves the Lord from having to deal with cross realm trips to build something quick and then leave again
5) Motivates Lords to care more about what's in their regions if they don't want something
