The odds of any of them knowing her are very slim. Even if they visit Japan, they could easily miss any and all references to Ayumi (or any other huge Japanese act) due to workload.

A couple years back, didn't Good Charlotte (or one of those types of bands) make a joke about liking Ayumi? And then a firestorm started about Ayumi dating one of them. It was insane. They knew who she was (presumably because they were on the same stage) but that's not the same as being a fan.