It's pretty easy. If he asked me again I'd just say remember the last time I let you borrow it & you said you were going down the street and 40 minutes later you returned.... and when he said yes, then I'd just tell him he proved that his word means nothing so saying he'd pay to fix it isn't good enough. Trust broken, answer no! You got one chance buddy, you blew it. (talk to the hand!)
I've let a handful of people ride mine. They all have/had their own sport bikes so their experience level is fine for me. They are all "real" friends & while they may not have cash in hand to pay me on the spot I know they would help with repairs in good time if need be. Plus they all have bikes if it really came down to it. Bottom line is if I can't afford to be without the bike then I don't lend it out. There are no guarantees.
Now, I of course have also had the displeasure of borrowing a race bike and wrecking it! I still feel terrible about it! I'll finish paying for the repairs in a month. I didn't have the money up front to fix it but with it being a race bike it wasn't "as" critical for an immediate repair. The owner paid to repair it, I'm paying him back. He on the other hand felt absolutely terrible on a personal level for my safety and the "what could have happened". All is well, we're still friends but we did learn a lot. I still ride other bikes but make it a point to have the "what if" plan in place before throwing a leg over. Oh & I offered up my busa straight out in exchange for the damage I caused to his bike before my butt ever left the ground from the wreck. Anytime I'm on someone else's bike I know my property is up for grabs. If I can't afford to work out compensation I just won't borrow.
Deb
PS: Try State Farm for insurance