They aren't offensive terms. At all. They are matter of fact situations for trans people.

Let's quit playing the word police, yes?

I definitely don't see "passing" or "going stealth" as offensive personally, they're simply terms to describe how the general population views your physical sex. Saying that someone passes just means that the general population will view them as their preferred sex, it has nothing to really do with how THEY view themselves or whatnot.

Going stealth simply states that someone generally passes 100% (not necessarily) and doesn't openly discuss their transsexuality. I don't see how that's an offensive term, could you possibly go more in depth about why they're offensive to you?

As someone who is trans, I don't see anything wrong with the term 'going stealth', but I don't like the term 'passing' for two reasons.

1) Passing seems to imply deceit (e.g. passing off a bad check, passing yourself off as something you aren't, etc.).

2) You would never say a cis guy was passing as male because they /are/ male, so when someone says a trans guy was passing, it sounds an awful lot like 'you look male even though you're /really/ not'.

If other trans people want to use the word passing in reference to themselves, that's fine, but I did not let others use it in reference to me. I preferred 'being read as male'; being read as male would apply to cis men as well and does not imply trickery on my part.

I'm a trans guy and personally I don't mind using both of those terms to describe myself.
However, I can see and accept the reasons for why other people don't like them - "passing" does seem to carry slightly deceitful connotations.

I don't think insisting that people are being "word police" when they find terms like "passing" or "stealth" to be offensive is acceptable. It's not about policing words, it's about words having meanings that can be oppressive, dangerous, offensive, or otherwise unhelpful.

Passing, for instance, insinuates that the person attempting to "pass" isn't really who they are. A man is a man. He is not "passing" as a man, he simply is a man. A woman is a woman. She is not "passing" as a woman, she simply is a woman.

Stealth insinuates that the someone is sneaking around and holding on to some deep dark secret that everyone should know about. This is also not true. Being "stealth" simply means keeping your personal life to yourself.

This is why words can often be problematic. Instead of insinuating that trans people are "faking" who they are or "lying" about it, we need language that is more truthful, honest, and less harmful.