Kicking a healer who doesn't DPS is considered kicking due to difference in play style, which has been confirmed to be a valid reason to kick someone.
This of course does not extend to any kind of harassment or mentioning of parsers during the process. However, if the person initiating the vote kick remains civil and avoids mentioning parsers, the healer would not have any sort of case against them. Even if they were asked how they know the healer was doing no DPS, they can just say they did not see an offensive skill from the healer in the in game battle log. So unless someone harasses the healer, they won't be punished for kicking the healer for not DPS'ing.
