I appreciate what you're proposing here, but I feel this would make the problem worse, not better.
First, the existing text does cover this:
Questions that are not a good fit for this site may be voted closed by experienced community members. Closed questions cannot be answered, but are eligible for improvement (and eventual re-opening) through editing, voting, and commenting.
What you wrote isn't bad, but it has two problems.
It is a "wall o' text". If the user can't read and comprehend the above simple sentence, the odds of them reading and comprehending 3+ paragraphs more, is slim to none.
It enables whining. Because it starts with "my question is valid" and goes on to say "your question might have been unfairly closed! here's how you can complain about it to anyone who will listen!" it will cause no end of friction. The reality is that most questions are closed because they were NOT, in fact, valid. So getting users into this "I done been wronged!" mindset is a very bad idea.
I am open to some refinement of the text that is there, but
No walls of text.
No whining or enabling whining.
Here's my proposed change:
Questions that are not a good fit for this site may be voted closed by experienced community members. Closed questions cannot be answered, but are eligible for improvement (and eventual re-opening) through editing, voting, and commenting. See How to AskHow to Ask for guidance on editing your question to improve it.