Personally, I had long held that the federal defintion included any knife that could flick open ( not even required to lock) until the recent add on of #5 as you quoted. I agree that if the pivot is loose enough, it could operate as a gravity knife, but as to the federal law, that should not be too much of a concern for you, unless you send it accross state lines as merchadise, or visit or live on a FEDERAL holding. States are not Federal holdings, so if you are concerned about a federal possession charge, then google what federal holdings are bound directly to federal law, and don't carry it there. We are mostly talking Federal buidlings, Indian Res, and things like that.
here is the wording:
Section 1243. Manufacture, sale, or possession within specific jurisdictions; penalty
Whoever, within any Territory or possession of the United States,
within Indian country (as defined in section 1151 of title 18), or
within the special maritime and territorial jurisdiction of the
United States (as defined in section 7 of title 18), manufactures,
sells, or possesses any switchblade knife, shall be fined not more
than $2,000 or imprisoned not more than five years, or both.