As always, anyone is free to post or not post and they should take whatever steps they feel appropriate to preserve their anonymity. That said, I feel somewhat mixed about such "warnings" in posts. Like I said, I have not ever heard about someone being confronted with something posted on this site. (And, if this was introduced by the PEB at the hearing, I would personally object to it, state that it was not part of the MEB, that you never had an opportunity to review the "record" they are trying to introduce, and I would attack it on the basis of they can't show it was you, it was not authenticated, is hearsay, it's irrelevant, and probably about 10 other objections that could come to mind- including that whoever was the proponent, which would have to be one of the PEB members, was thereby disqualified from hearing the case). In my almost 7 years of representing members at PEB's, I have only been involved with, if memory serves right, 3 cases where the PEB undertook their own "investigation" and sought to introduce evidence gleaned from online research (none of the cases involved this site- one, that is most memorable, was where a board member questioned the PTSD stressor, stating that his research showed no deaths or obituaries of the named Soldiers. After a brief recess, I presented a copy of both an obituary and a medal citation that described the details of the attack). So, bottom line, I have not seen any significant "research" or monitoring of this site. The normal format of the PEB does not really lend itself to such research and introduction of evidence by board members and, finally, another measure of "protection" is that the board really has a high workload and does not have time to spend on here looking things up and trying to connect them to present cases. (On the other hand, I do know that many board members are aware of this site- I have discussed it with several of them).
So, this loops back to my initial point. People are free to post or not and are responsible for their own words. But, the mixed feelings I have is that this site has helped, and continues to help, many servicemembers by answering their questions, providing information and references, and giving a sense of community and shared experience. I don't want people to feel scared coming here.
As for your case, it strikes me that a denial of a summary adjudication is not that unusual. They are both granted and denied all the time and I would be hard pressed to find either a causative factor or even correlation between what is posted on here and the outcome of a request for a summary. All a denial usually means is that the board is not convinced and would like to hear additional evidence. Though you have deleted/edited your posts, from what you posted before, I would have been very surprised if they granted a summary. I don't know what is in your case file, but if things were as you suggested and there was a lack of supporting evidence available to you to submit (though, it may have been in your file), I am not sure I would have even bothered with a summary adjudication request without such strong evidence. And, while it is, I suppose, possible that a board member stated, "no, we are denying based on online posts" this seems an extremely far-fetched scenario. Normally, the board would just tell your counsel their decision without explaining something extraneous to the record.
Now, I may be 100% wrong and the PEB boards have been stalking and monitoring this site. However, especially with the AF board, this seems extremely unlikely. I know all of the board members, the staff, and (with the exception of several newly assigned attorneys) the attorneys there. I strongly suspect that your fears are not founded. Either way, I hope you get a great outcome.