I understand how misinformation can be annoying but in my opinion, move on. You've done what you could to try to convey the correct information and the support behind it. That's all you can do. They are probably a volunteer run organization with varying skillsets and limited time.
I cringe when I see illogical and/or erroneous information posted on family trees. But I also know that it happens to me too. I'll run a Family Tree Maker error report which points out potential discrepencies and wonder how I could have made those mistakes and wonder how many more might be in my database that aren't detectable by the error checking process.
As you pointed out the lady who posted it probably made an innocent mistake. It happens to all of us. That is the nature of data that is sometimes based on illegible or poor records, memories, or is subject to common errors like transposition of numbers.
Be proud of your own thoroughness and happy to convey the correct information in the future to someone who may inquire why your data is different.