http://revach.net/article.php?id=1699

Section: Halacha   Category: Tshuvos
Standing Up When You Are Holding a Sefer Torah
The Shulchan Aruch (Yoreh Deah 244) says that even a person who is learning Torah must stand up for a Talmid Chochom. If a person is sitting down and he is holding a Sefer Torah and a Talmid Chochom passes by, is he obligated to stand up for the Talmid Chochom in these circumstances?

The Shiyure'i Bracha says (Ibid) that he should remain sitting and he should not stand up for the Talmid Chochom. Even though it is a Mitzvah to stand up for a Talmid Chochom, in this case that he is holding a Sefer Torah the Mitzvah doesn't apply. However if it possible to place the Sefer Torah down on a safe place he should place it down and stand up for the Talmid Chochom.