Vegetto
said
:
based on what official source ...?
I cannot direct you to an official public source for that. There used to be a sticky in the Discontinued Items Forum, where Jagex provided a list of what items could be traded there, and I believe the pet token was listed there. I do not know when that sticky was removed or why. (I suspect the plan was to add the list to the Forum Specific Rules, but that did not get done.) While the wiki is supported by Jagex, it is still a community driven fansite and not "official". Allowing items that Jagex has not identified as "discontinued" to be traded in the Discontinued Items Forum, could imply a greater value for those items than they currently have and would cause quite an uproar and possible loss of value should those items be re-released in the future.
As for the misplaced hero items, while the preferred forum for those is the Business, Services and Miscellaneous Forum, several of those items also provide boosts and benefits to skilling so is is understandable that some players might place them the Weapons, Armour & Skilling Supplies Forum. Those threads might get less exposure in the wrong forum, but there is very little risk of a change in valuation or other harm.