A HUGE percentage of couples meet through work.
It's not inherently wrong, or something inherently taboo. (We've all been told not to stick our pens in the company ink, but... time and time again we also see examples of happily married couples who met on the job... Bill Gates' wife worked for Microsoft, The Obamas met while they were working together, Ryan Reynolds & Blake Lively met on the set of Green Lantern...)
So it feels like the message here is, "It's fine when it works, and it's totally not fine when it doesn't work." The only way to know if it's fine is to ask. It's not really something you can make universal rules for. To each their own, right? (I would say a wedding ring means someone is off limits, but affairs happen all the time too.)
Point being, it has to be something more than, "It's OK to hit on someone if they are attracted to you." I think hitting on someone is inherently a compliment. But if they say no, and you try again, and they still say no, well probably don't try a third time. This guy is apologizing for being called a creep after hitting on someone once... man, that's rough. You don't know until you try.
There needs to be a little more flex here, it can't just come down to, "Anyone who we don't feel attraction to should be fired if they pay us a poorly worded compliment or tell a bad joke." Stalkers, sure... people who try and leverage their position in the company to get laid (with the implication), yeah... but just some guy who tries to clumsily flirt with a girl and can't play it smooth because he's fundamentally not a player and actually likes her... come on, cut that guy some slack.