Notice in the story that he had his AoE heal that he was plopping down from time to time. This is the top-tier ability for healing sages/sorcs. He was just a crappy healer.
or didn't think they needed to heal anymore then that with 2 other healers in a group, and chose to dps instead.
seriously, sometimes Czerka flashpoints in normal mode give you very odd compositions, since they are not role specific. there are times when the group will let you respec. and there are times when there's no point. I know that on my sorc at least, I would gauge how the other healer is doing and if I see that they are casting and healing and generally making whatever healing effort I may make into overhealing, all the while things are taking forever to die becasue we only have one person doing the damage in a group? I'll just throw lightnings around instead, occasionally plopping down revivification. why? becasue at that point, me killing things will do more good than me trying to heal the damage that's already being healed by someone else.
its pretty similar for me i story mode Esseless/black talon. if I happen to be slotted as a healer with another healer? I adopt to what they are doing. if they just dps, then I go full time healing. if they heal, I pick up dps instead. and in case when the other healer decided to only dps on trash (becasue naturally people don't take damage on trash amirite? >_> ) and then would suddenly switch to healing on bosses, I just adopted and switched to dps on bosses, while healing on trash. sometimes rocking the boat is needed. most of the time, I personally prefer to adopt to the group - nicer and smoother that way. amusingly enough, people rarely notice when I do that as a healer/tank, but they definitely notice when I do it as pure dps :/ I guess becasue you get so used to impatience and grumbling, playing with someone willing to adjust is a novelty.
(and no, I'm not the person that original poster was talking about, unless the run they are talking about happened at least 3 months ago. becasue that was last time I pugged normal mode Czerka, nowadays I either solo them, or run them on hardmode with guild)