Anyone who is abusive to other players over a DPS score obtained by a 3rd party program deserves a temporary ban -- not for using the 3rd party program exactly, but rather using for malicious intent.
Not saying that the player in question was being abusive.. I have no evidence of that... but we all know the type...
Ont he other hand...
^^ This is a tactic often used by elitist individuals who are convinced they alone represent the attitude of the group. ^^Likewise they could report you, and your low DPS, for disrupting their gaming experience. It's not a one way street. You are in a group and the interest of the group comes before the individual.
In a random DF/PUG, you'll find often good people who are willing to be patient and teach people the fight, just as you'll find sometimes get impatient elitists asshats who think the best/fastest way to win is to bully people into it (It almost never works BTW, but they keep trying...)