Originally posted by delnz
there are many many threads in the chess forum about "why won't my opponent resign".
the second and more important sticking point you have is that the analysis board does not check for move legality, so it can't "prove" anything. This is by design so it cannot assist you.
I guess you're right, although it would be at least possible to set out a series of conditional moves and submit them to be read by software on the RHP servers. They could then be shown to the other player with the option to resign (or draw if there is a forced draw). But I guess it's probably not worth the extra programming.