Sounds like your "so called" healer either, forgot to untick the healer option in GF, in which case he's a moron or deliberatly left it ticked to get a group faster, which makes him both a moron and a jerk. Had a similar thing happen in Colicoid Wargames, a Shadow Tank (lvl 44) joined with only 8k HP, was using Force Technique, didn't guard, didn't taunt, kept using Force Cloak to drop agro, didn't have a shield equiped and was in DPS gear, he got vote kicked very fast
Having the GF do a build and gear check could also raise some problems. Firstly the build check, I know a fair number of Guardian Tanks who run a Hybrid build, mixing both the Vigilence tree and the Defense tree, if fact most of these builds have more points in Vigilence than Defence, so there is a risk that they'd be catatgorized as DPS when they are in fact Tanks.
I am also opposed to a manditory gear check of any sort, and short advisory warning that "you may be undergeared for this Instance" would do, but locking people out based on gear over looks 1 important thing, skill can make up the difference!
Case in point, early last year our guild was running EV in Storymode for the first time, we had 6 guild members and a couple of PuG DPS. 1 of our guild (a fresh Commado Healer) was running in Recruit Gear while one of the PuG DPS (a Sentinel) was in full Columi. The Healer was brilliant, despite his lowly gear he kept my Tank and the DPS in my group up with almost no problems at all. The Sentinel on the other hand earned the nickname "Mr Squishy" on the grounds that he died in every boss encounter and half the mob encounters. Based on their gear the Sentinel would be allowed to run LI HM but the Commado wouldn't, but I can tell you right now who I;d prefer to run LI with