Beis Shammai say that you don't do Semichah on an animal on Shabbos. The reason is because it's like riding an animal on Shabbos. Why don't we say "Ain Shvus Bamikdosh"?
Dear Aaron,
See Tosfos DH veha'Elyon (Eruvin 102b) that there are cases of Shevus ("Shevus Gedolah") in the Mikdash that are forbidden and he adds that there are many examples such as
1) not allowing the placing and removing of the rods under the Lechem ha'Panim and
2) rinsing the Azarah according to R' Eliezer (Shabbos 95b DH Shara).
All the best,
Reuven Weiner