Even if they only made 1 appearance the fact they had a WWE contract makes them an ex employee. Yes they are also ex ECW as well so technically both of ye are right. Looking at from an everyday pov they are more recently ex wwe. I mean your not going to say oh they are ex ecw,wcw, njpw, wwe guys now are you? You would pick the last company they worked for.
I'd pick the most notable company they worked for which was wwe.