Don't do it.
This article satisfies Squid Commo Objective #2: Suffer not bullyery.
"He is not well bred, that cannot bear ill-breeding in others."
- Poor Richard's Almanack
Any respectable martial art would admonish its students not to use their newfound power to pick on others. Consider yourself admonished. Work to improve yourself, but don't go around criticizing or ridiculing others for what you think is poor language.
One reason is that you might be wrong. Learn from the Army instructor who saw the statement, "Never agree not to escape" in a memo we all had to read. He wrote "double negative" over it indignantly, in ink, no less. Well, he was wrong. What he did is not unlike some rookie running out and picking fights because he learned a new kick in karate class. Sometimes you know just enough to embarrass yourself.
Another reason is that running around correcting people places you in the undesirable position of having to be right all the time. Once you strap on the holsters of intolerant correctness, you have to watch your back at every turn. Young wordslingers will be stalking you, looking for a chance to gun you down. You get cautious, even paranoid, and that tends to take all the fun out of it. And it must be fun for you to get good at it.
As you get more advanced in PUG, you'll find that there's often room for informed disagreement. It's difficult, or at least intellectually dishonest, to slap people around with hard and fast rules where relatively few exist.
The best reason, though, is that, unless it's your responsibility to train the folks you're slapping around, it really serves no good purpose. So don't menace the unlettered unnecessarily. Be the admiration of your 360-degree feedback circle. Wow them with your superior communication skills and your benevolence.
Just in case you're wondering...
"Never agree not to escape" has two negatives, but they negate two different things, not each other. Never negates agree, and not negates escape. This is not what we call a double negative. It's just two negatives.
Double negatives conflict. "Don't never agree" would be a double negative. Both negatives negate agree and, as a result, cancel out to yield simply "Agree."
But...
Surprise! Just as the NRA would suggest, double negatives don't kill; people who own double negatives kill. That is, double negatives can be used for good.
Good Guy with a double negative. Sometimes the canceling in a double negative is intentional in order to yield a positive, as in, "It's not unlike some rookie…" The two negatives cancel, resulting in, "It's like some rookie…" Hooray!
Bad Guy with a double negative. Sometimes the canceling produces an unintentional outcome and gets innocent people hurt. "Ain't nothing I can do," turns into, "There's something I can do." The meaning is flipped around from what was intended. Boo!
To correct an intentional double negative, remove both negatives. (Although it's debatable that this type of double negative even needs correcting.) In our case, that leaves us with, "Agree to escape," which is certainly not what the author intended.
To correct the unintentional double negative, you remove one of the negatives. When we do that to our statement, we get either "Never agree to escape" or "Agree not to escape."
Ain't neither of those what the author intended. So it's not incorrect after all. Not hardly.