Tank *way* overreacted, but I can understand his frustration at the start. Even though SM Esseles and SM Czerka flashpoints don't really require any roles (and most pulls could be solo'd even without a companion), I personally feel like it's still polite to let people try to fill their roles if they express an interest in it. Half of tanking is learning the mindset and flow of a run, not *just* about abilities or cooldowns. People may be running them for practice. If I get into an SM with someone who is trying to tank (whether or not they're succeeding) I don't mind waiting half a second to let them pull ahead of me. If they're exceptionally slow or don't seem like they care, then I'll jump ahead as long as the rest of the group seems to be on board. No reason to go out of your way to make a tank's life miserable unless you have to. Still, from the other side of things, no reason to get so upset if you have an obviously dense DPS either.
Most "tanks" in Esseles/BT aren't even tanks yet as they lack the tanking-stance/cell/... which you get with level 14.
So I don't see any reason to take them serious when they rant about not letting them tank (HS and above is a whole other story)