I agree with eliminating any "treaty" preventing profit takers from exploiting space. Stoopid in the extreme, and always very detrimental to progress in any area.
I am very against any scheme that will provide any international agent an essentially infinite power to extract money and resources from the economy. I don't see any way an "asteroid deflection" capability is anything other than such a scheme, and until I see solid cost figures, numbers and probabilities assigned to such a system, that's the position I'll maintain on such schemes.
You are quite correct to be suspicious of International agents. I share your suspicion.
However, even though I am proposing an agency which acts internationally, even interplanetarily, I did not recommend that it be international in its make-up.
Recall that I expressed concern about a military hazard as well.
I think the United States should be the progenitors, suppliers, and controllers of this force, if for no other reason that to see to our own security.
We could, of course, provide openness to allay the fears of our suspicious neighbors, and even allow them to contribute to its cost of maintenance, but we should unquestionably maintain control.
For the cost, I could recommend ways to get massive amounts of manpower and equipment into space for a bargain, considering, but that is a discussion for another time.