Ozgal, your camping-fuel container was disallowed because of the flammable vapors, not the steel container. This rule far predates 9/11. I remember having to find destination vendors who stocked containers that fit my backpacking stove by phone and fax, back before the internet.

I generally travel several times a month in the U.S., have had no problems carrying my SS water bottle. When it was first given to me (just before the concern with phthalates went public, maybe 2007?) I was asked once what it was, replied "my empty water bottle" and that was it.

They are much more common now, but you might print out the page(s) about things allowed for children from TSA's website just before you go, just in case. Hopefully you'll encounter no difficulties.

Wishing you a wonderful visit.