Nah, I think they can rant as much about it as they want, nothing is unprofessional on Twitter - have you seen the state of of it?
Actually I think they are using correctly, you are suppose to post something to provoke the most reactions you can.
But getting back to the point, I agree, it is not really a problem if you actually verified your input before blindly running ffmpeg on it - like people are not just downloading random files and running ffmpeg on it are they?! You would think if you are rolling ffmpeg into production code you would know the ins and outs of it.
Anyways I feel for those open-source maintainers, they must have so deal with so much noise.