What probably would have happened, in the case of grammar
No, it doesn't make it a scam, but it's certainly unbelievably sloppy for a company promoting its writing service to make such basic mistakes. If I owned a website, I'd be damn sure to avoid such problems, and I'd let the 'programmers' know what needed changing before it went live. I'm not even sure that I'd let said 'programmers' come up with the copy for my site. As a customer, I'd immediately lose faith in that site.
A scam, I guess, is when you attempt to make a gain by offering something that you can't really deliver, e.g. taking money for an essay that's supposed to be a 1st when you know it's going to fail. Everyone makes mistakes, but the question of whether it's a scam comes down to whether or not you've acted in good faith. It's often quite hard to tell on an individual basis, but look at the experiences of a number of different customers and the picture usually becomes clearer.
I think you're right that this forum is often used by BUFFOONS and BLOWHARDS, but I also think that in this particular thread, you're kind of defending the indefensible.