According to R.Y.S .Elyashuv,* Even if you are in a Shul
where the Minhag is to stand up for Aseres Hadibros, you
should remain seated, because standing up
(for Aseres Hadibros) is Neged** Halacha***.
*The Igros Moshe (O.Ch.4:22) argues and holds to follow Minhag Hamakom.
** Teshuvos Harambam (Ta'arumos Haminim)
***The Tashbatz does bring this Minhag