Tldr: Gallus is pulling the "blame the victim" card. Even in an example made specifically where the sole fault lies with the healer, the tank that died is the only responsible because the healer's feelings might get hurt.

Furthermore, if we're going to make it about feelings, doesn't the tank feel harassed/trolled in the first place because the healer let them die? That would preclude any harassment felt by the healer being called out/kicked.