Considering what field these people are working in, mistakes can slip out very easily. We like involving our own personal experiences or inquiring after other people's personal experiences and when you work in the same or a similar field, it makes sense to talk about the topic you're both familiar with. The trouble is that that field in this case is condoms. One can very easily inquire after or provide one's own personal experiences relating to sex, and thus cross a line.
That said, you have an opportunity to weave in a message when writing fiction. If you're going to let this character make all these remarks and ask all these insensitive questions without any pushback being given by any person or anything in the plot it'll come off as "Oh look at how quirky and tactless this character is, haha!" when in reality this stuff is ultimately sexual harassment.
It's OK for the brand ambassador to not realize that she's sexually harassing this person; That's usually the defense. Just call it out though.