The warning is useful in one regard, but the balancing is more important, I think.
Consider this: Last night, by accident, I drank my toilet water instead of my clean water. My strength immediately shot downwards and I doubled over in pain. I decided to handle it by eating my one and only dose of royal jelly.
In that case, my mistake had serious consequences, but I was able to make a choice (to jelly or not to jelly) to modify the consequences (wait it out, or be out my royal jelly). In Crawl, a similar mistake might cost you valuable potions or scrolls as you struggle to correct your mistake.
But here, in the stunlock example, there’s no choice, no play. You are stunned for 15 consecutive turns: proceed directly to YASD. I don’t think that’s particularly interesting or fun.