He seems to appreciate aikido, but has a useful critical eye for it too. Here are some quotes from the master himself on aikido.
“I like Aikido. It is perfect Judo technique. One thing though – in real life perfect Judo is very hard to do. In real situation in order to get technique you have to put a foot in the way.” (referring to the difficulties of pure Te waza)
"Tai Chi is meditation by your self. Aikido is meditation with some one else. Judo is meditation against someone."
Matl sensei has another quote when he asked the Round Rock aikido teacher to shiai with him. "You aikido guys need to shiai every once in while. Otherwise you are just sitting on the couch, eating pizza and smoking cigars." While this is a somewhat cryptic and humorous quote, especially if you know the man, I think it makes a point.
I think there is a theme building in Sensei’s quotes and observations about aikido training. I am hearing him say in the subtext of his quotes that aikido is a great art, but a lot of aiki training methods hover around some of the gritty difficulties of a martial encounters.
I think his observations are interesting and worth including into your own evaluation of aikido. I think we aiki artists can justifiably rationalize some of his observations away, but returning to face them every now and then is probably wise.