It wasn't advice and it wasn't a "gezeira". It was a psak.
I'll leave to those who are more well versed in the sugya of גזירה שאין רוב הציבור יכול לעמוד בו to refute the argument but to me (as a simple pulpit Rabbi) it sounds far-fetched that a psak becomes invalid if people don't listen.
Also look in the Rosh in the sugya of שיהה/הטמנה about being realistic that ppl not gonna listen
הנח להם לישראל שהם אדוקים במצות עונג שבת לא ישמעו לנו להחמיר...
Just giving historical context to the mess that’s happened in Lakewood and elsewhere perhaps.