I am not a PA resident; but have relatives and friends in PA.
I'm not able to quote the law; but I can't recall a duty to conceal being connected with an LTCF. I'm pretty sure open carry is not barred in PA.
You can start by checking the map on this site, and following the links to relevant PA laws. Nothing like seeing the law for yourself.
It looks to me like the Sheriff has mixed his tactical and social advice with the law.