I think one can make certain assumptions about relative probabilities.
It's not that unlikely for all but 5 people out of a reasonable-sized realm to stay home from a tournament.
It is highly unlikely for all but 5 people out of a reasonable-sized realm to become infiltrators.
In any case, I agree with Indirik: whatever the analogies you want to use, rewarding people for staying home from tournaments is qualitatively different from rewarding people for changing to a specific class. I would say that there are various reasons for this, including the aforementioned purely quantitative aspect, but also the fact that the reason there's a tournament IR in the first place is to allow and encourage people, especially newbies, to get out beyond the borders of their own realm in a non-combat setting.
