So, according to you, tags go by object, regardless of method of use. It follows that a javelin is, always, a melee weapon. Note that under that set of rules, 1 lb objects (the only weight for thrown improvised weapons), despite having an entry in a melee weapon table, cannot be used as improvised melee weapons because they are also improvised ranged weapons. Further note that (extremely) hypothetical weapons (maybe there are some in the AV, I rather doubt it) with worse base state lines than the improvised weapons but with really good tags could then be used as improvised weapons while keeping the good tags.
Of course, for the case of melee weapons with light/heavy thrown tags, you get the more permissive case of weapons with a combined melee/thrown weapon-table entry, so you can't argue your way out of Int. Blademaster+thrown javelin by saying "an improvised weapon doesn't count as the non-improvised use and vice-versa because they are separate weapon table entries".
(btw, I was wrong on 2-handed imp. melee weapons, the weight range s 6-12)