Your premise is that the competition has incorrectly grouped styles outside the authority of the BJCP guidelines. However, the guideline itself rejects your premise:
“Competitions do not have to judge each style category separately; they may be combined, split, or otherwise reorganized for competition purposes.” 2021 BJCP Style Guidelines, pg xii
Additionally, you presume that this grouping is “not fair to the participants to enter category 5, but them compete against beers that do not meet the BJCP standards for category 5.” The BJCP addresses this perception as well:
“Competitions may create their own award categories that are distinct from the style categories in these guidelines. There is no requirement that competitions use style categories as award categories! Individual styles can be grouped in any manner to create desired award categories in competition; for instance, to evenly distribute the number of entries in each award category.” 2021 BJCP Style Guidelines, pg iv
What say you, you ask? From what I can tell, the guidelines don’t dictate to the competition. The competition can do as they see fit.
My unsolicited advice:
1) Brew your best beer every time you brew and categorize it by how you interpret the guidelines.
2) Submit your entry following the instructions for the competition to a T.
3) Save two beers.
3a) Crack one the day of judging and take notes on a BJCP score sheet with the style guidelines open.
3b) Crack the second one when you get your feedback with your notes open.
4) Try to understand the judges’ feedback based on what you taste, your notes, and the guidelines.
Like par in golf, you aren’t competing against the people in your foursome. You are competing against par for the course, or in this case, the BJCP style description for the style you submitted your beer under. Just like in golf: it doesn’t matter how. It’s how many that counts. It doesn’t matter what you intended to brew. It matters where it best fits.
BTW, these are my personal BJCP favorite quotes:
“The Style Guidelines are not the Ten Commandments. …Don’t treat them as some kind of Holy Scripture.” and “We are not the beer police.” 2021 BJCP Style Guidelines, pg vi