By definition, an unrestricted one-on-one fight is more likely than a specific subset of one-on-one fights, since the first possibility includes the second.
But neither is likely at all.
Also unlikely: picking a fight with someone who weighs about the same amount you do.
I don't think your logic follows. Unrestricted fights and restricted fights are both subsets of the set of fights, but restricted fights aren't a subset of unrestricted fights. By definition, unrestricted fights are distinct from restricted fights.
Either way, I regret pursuing this topic and won't comment on it further since I feel this is a discussion not worth having, reading, or writing. I don't write that to be rude, just as an attempt to hold myself to some standard for discourse.
I expressed myself poorly. The unrestricted class "one-on-one fights" includes the restricted class "one-on-one fights where both parties agree not to wrestle".
For some martial-arts, it may be necessary to account for the likelihood that bystanders will actually be close enough to be able to intervene before the fight has concluded.