This question - Coworker won't accept apology for my stupid mistake - is fake.
It is impossible that someone would mistake a bereavement letter for a new baby letter. The cards are very, very, very different.
a - It is impossible that someone doesn't at least read one message in a letter - even briefly. You would notice the lack of "congrats" and the presence of "sorry for your loss".
Even if you can believe someone is so fictionally clueless, what, that nobody else read what other's wrote? I always have a quick look at what other people wrote, someone would notice the weird, inappropriate message.
Who writes a message without a name? Or a new-baby message without the word "baby".
The message the OP claims to have written is so perfect - no name, can be read both ways, doesn't mention the word "baby" at all. It even has the perfect "bring you dinner" line, just to push it over from stupid to sexual.
Also, OP would be fired for this, if they did accidentally do it.
This can only be a fictional account - written by a new user. It's not helpful in the future - it's probably just some writer trying out a scene in their book.
As an aside - i push for fake questions to be removed because they encourage other fake questions. it wastes the community's time supporting larrakin efforts. i enjoy coming here to get other people's viewpoints and thoughts on (for me) practical management issues. i don't want to see the site overrun with "interesting" quandries and purely theoretical discussions.