Sforno on Leviticus 21:12/ספורנו על ויקרא כ״א:י״ב

1ומן המקדש לא יצא. According to Rabbi Saadyah gaon, this means primarily joining the funeral cortege which requires leaving the holy precincts.

2ולא יחלל את מקדש אלוקיו, so as not to desecrate the Temple of his G’d, as people would conclude that giving honour to the dead is more important than to remain within the sphere of G’d’s immediate presence, something he enjoys as the exceptional privilege of being exposed to on an ongoing basis.