Perhaps there was a nuance in the original Japanese, but as I read the deal in the fansub and thought about exactly the question "are there any loopholes in this?", I was sure that the answer was no and the language completely excluded any clever tricks Kiritsugu pulled or could pull... until I saw that the shooter was Maiya (rather than any other faction), at which point I was furious.
(And if the contracts are that easy to subvert, Lord Kenneth should have easily spotted the loophole as a pretty devious and experienced mage himself.)
I'm also a bit skeptical about the contract implementation, but from a plot perspective it doesn't matter very much. Even with Excalibur sealed and her left hand disabled, Saber outclasses Lancer. Even without the self-Geis scroll, Kayneth has no other option for evading Kiritsugu. It was probably still a bad writing decision to add a plot hole simply to make Kiritsugu look badass.
(A better subversion, IMO, would have been to have Kiritsugu not inherit the Emiya family crest -- which is what it looks like from the perspective of Fate/Zero anyway. Then the ...
This is the monthly thread for posting media of various types that you've found that you enjoy. I find that exposure to LW ideas makes me less likely to enjoy some entertainment media that is otherwise quite popular, and finding media recommended by LWers is a good way to mitigate this. Post what you're reading, listening to, watching, and your opinion of it. Post recommendations to blogs. Post whatever media you feel like discussing! To see previous recommendations, check out the older threads.
Rules: