Right, and to make it explicit for some people following along who are wondering why companies have that policy... It's to prevent predatory and abuses of power. There's a power imbalance that can easily lead to exploitation.
Because it's likely sexual harassment. In two ways:
1 - did she feel pressured to have a relationship with him? It's hard to have genuinely free consent when he can make or break her career; and
2 - sexual discrimination towards every other employee. Did she get benefits from the relationship? It's more than fair for the rest of the employees to wonder if they'd also been eg sucking his dick if they would have gotten better raises, faster promotions, etc.
All 42,000 employees should be held to the same standard, otherwise you will end up with all kinds of problems within the company.
Company leadership should lead by example as well.