Seichel Hatorah,
There is daas torah also on how to warn the public of a possible michshol.
Did you ask Rav Shmuel Kaminetzky shlita or Rav Shlomo Miller shlita:
1) if you should make a post on YWN telling everyone that most retzuos are posul !
2) and calling people who don’t change today a karkafta dlo manach teffilin
3) and you should borrow someone elses?
Compare the way that Rav Eliezer Ginsburg made the announcement to yours.
I will quote the public announcement by Rav Eliezer Ginsburg shlita in the Flatbush Jewish Journal of March 11, Page 3.(Archives are online.)
Rav Eliezer Ginsburg has issued a warning “It is possible that instead of coloring the retzuos a plastic coating was put on them, which is not acceptable.
If you suspect this is the case with your teffillin show it to a reliable sofer. ”