I'm not really sure how much staking-out of high ground is even possible until one gets closer to economic realization. Even if some treaty said that "Any touching of the asteroids is forbidden forever, with utter seriousness", one could safely enough do the R&D necessary to make grabbing them and chopping them up more practical; basically all the capabilities you'd need for asteroid mining can also be used for satellite launch, automation/robotics, improved astronomy and telescopes, and similar warm and fuzzy applications. The astronomy stuff would mostly fall under 'pure science', unless you can convince somebody that it will help detect ICBMs; but launch capabilities and improved robotics and remotely automated process research have a variety of plausible commercial applications even if the asteroids are off the table.
On the other side of the coin, highflown expressions of legal principle are usually given a great deal of latitude until they actually conflict with the interests of the nations that you need to sign and obey them. So long as the prospect is sufficiently science-fiction, anyone willing to spend a lot of time hounding UN delegates is more or less free to write whatever they want. Were somebody to step up to the table with a vaguely plausible plan, however, it's hard to imagine that they'd have much trouble finding a country large enough to be able to ignore the consequences and more than willing to do so in exchange for a cut of the take.
It seems to me that team lawyer wins more or less by default so long as the implementation isn't worked out(both because it won't actually be happening; and because there will be relatively little resistance to opining against it); but team mining will win more or less by default if they can actually make it cost effective; since laws national and international are bent, broken, or rewritten all the time for markedly less profitable(and much more ghastly) ventures.
Until that time, the posturing is symbolic(either banning the practice or laying claim to rocks you aren't already on course to intercept). If the law says nobody can do it; that will change once somebody concludes that they can turn a profit by doing it; and if I get myself crowned God Emperor of the Kupier belt now; I'll still have to get my tech up and running before somebody else does, or the claim will do me little good.