Regardless of legality, a lot of people still see hiring a sex worker as something shameful. Even in countries where it's legal there's a fair amount of public concern over sex workers and human trafficking. (and please, let's not have that debate here.) And/or that hiring a sex worker is perceived as a "means of last resort" for "incels" who do not meet conventional standards for physical attractiveness, "have no 'game'", etc., and "can't get laid".

If it got out that he'd hired a sex worker, that fact could cause serious damage to his professional reputation. Also, the company may not want to be known as one that hires the sort of people who would hire a sex worker, even if it's done with personal funds, on one's own time.