Before Dishonor was not the book it should have been, but I have every confidence that Peter David and Margaret Clark gave it their best shot. And to assume that they did not is just needlessly mean-spirited.
So we have..
Assuming someone gave something their best and it ended up sucking is not insulting.
No, it's not, because it's a fact of life that you're not going to succeed every time you try to do something. If someone says, "I think your book was not as good as it should have been," that's not an insult to a writer with a good sense of how to take criticism -- he/she will understand that not every effort will be as successful as others and that everyone will have a different reaction to their work.
Saying, "You didn't try," however, is deeply insulting. It's an attack on a writer's professionalism and personal character.
There is a huge difference between criticizing someone's
work and criticizing someone's
character. Accusing PAD of not even trying is the latter, not the former.
ETA:
I look at it this way:
I was an actor in college, and one of the things that you inevitably must learn is that while there are objective ways to evaluate a person's performance to an extent, to another extent, the quality of an actor's performance is subjective.
What that meant was, I had to learn to differentiate between legitimate disagreements about how a character ought to be played and attacks on my professionalism as an actor. If someone felt that the character I was playing should have done this or that for logical reasons, then that's fine. But if someone just assumed that I wasn't even
trying to give a good performance, then that was an attack on
me, not my performance.
You can legitimately criticize an author's work. But there's no need to attack the author himself.