Because religion should not mix with business.
CEO's should be sufficiently self aware to understand that they should not be foisting their beliefs on the company and their employees and customers.
Being unable to recognize that is a very bad tell about a persons judgement.
Person doesn't obey your arbitrary rule; you clutch pearls.
Of all the openly religious people, Gelsinger did the least to mix business and religion. Whereas an irreligious person like Peter Thiel says some really wacky religious stuff.