Hey! That was me at the Poly pool enjoying the slide before going back to my value resort!! Seriously though, those people (if they even exist as I find it very unlikely that you heard them talk about pool hopping at the CR monorail then also happen to see them from your room in the Poly pool) very well could have been
DVC members, as my mom's neighbors are DVC members but stay at ASMo once a year since they have 2 young boys who love Buzz Lightyear. However, the OP is not talking about pool hopping, she's talking about letting an 80+ year old great-grandma sit in a chair with her family.
Yes, I'm sure that if every Poly guest brought their families to the pool it would be mobbed, but the odds of that happening are so unlikely. The majority of people vacationing at the Poly do not have relatives in the area that they smuggle into the pool.
I totally agree with 'OnemoreTry'. We'll be at the GF in just over a week and if anyone wants to bring grandma along, that's fine with me. If I were at the Poly, I'd give up my seat for your grandma, or any elderly lady enjoying her great-grandkids, as at that age they may not have too many opportunities left. People should think about the overall picture of how having grandma there will not damage your vacation, but will create great memories for her and her great-grandkids that, in my opinion, are much more significant than the memories of telling a non-resort guest grandma that she can't spend they day with her resort guests family.
But if you really want to appease the people on this board, get her a soda from Captain Cook's and drag her chair that she is entitled to use from Captain Cook's over to the neighboring pool area. That should calm the DIS pool sitting police.