The proof is in the "Do"...
AikiDO is not meant to handle trained fighters. It is a means of gentlemanly self-actualization with some protection benefits. The term "Do" should tip you off. Even hard sparring karate styles like Kyokushinkai or Chinese combat sports like San Shou, can't hang with real Thai Boxers. It's been proven over-and-over again. You see no "Do" or "philosophical way" connotations in those names either.
As far as kickboxing goes, Thai Rules Muay Thai is the apex. I like Savate and Shidokan, too. The ploumb, as pointed out by Sev*, is a very good infighting technique for one versed in knee strikes and leg kicks/sweeps/destructions. It can also be used as a standing neck crank, and it hampers concentration greatly! Grappling counters are the best options for loosening the ploumbers grip, hahaha! Didn't mean that bad play on words. This includes trips, hooks, hip throws, "spearing the ball" slams, single and double leg takedowns, etc.
I don't doubt aikido teaches the theory of these counters, but it just doesn't practice them on resisting partners. Especially hard as nails Muay Thai fighters, ready for bone-on-bone strikes and blood splattering.The truth can really hurt! Muay Thai may be the most external of all striking arts. The epitome of Wejia!!!