Namie saw Ayu live on 2 or 3 different concerts, so, I guess Namie likes Ayu.
Ayu also said in interviews that she respects Namie... And wasn't there something about Ayu actually going to Namie's concerts a long time ago? I can't really remember.
If anyone on the jpop market knows how cruel their market and the media can be, it's those women... The fact that they survived the industry all those years alone probably makes one respect the other.