Jinx: Where does the burden of proof lie?

Say that a co-founder of Fluther is trying to renege on a fair and square jinx that happened over IM. Now, the commonly known rules of jinx are as follows:

Jinxer says “jinx” and then “1 2 3 4 5 6 7 8 9 10” before the jinxee says “blackout”.

Now, according to this proof, I was successful. However, the other founder claims that he actually sent it before.

So, what happened is that both of us sent the last transmission as the other was typing, and that iChat shows your local transmissions before they’re sent.

I say it’s the jinxee’s burden to transmit blackout before the jinxer has finished transmitting “10”—which is what my proof shows.

What says fluther?