Simply kick the bad healer from group, if every group kicks them for acting like a tank they will not be speed running anything but duty finder looking for a group that won't kick them for being a tool.
If your in Tam Tara with a new player who never played a mmo or a tank before and we all know tanks have low agro control at those low lvl's , especially vs high geared players, then the real bad player is the healer for not controlling their agro and helping to teach the tank and possibly the group how to work together and that it's the tanks job to get hold and maintain agro and it's the group's job to watch and control their agro . I have a ilvl 111 whm and I can control my agro in low lvl dungeons even with a new tank I will very rarely get agro .
It's just bad players who think speed = skill.