In Arkham Horror, do you ignore counting items that can't be lost or stolen when going insane or unconscious?
While the ruling may seem a little bit weird, everything they say in the errata section makes sense.

During an unconscious or madness scenario, you are the one looking at your items and choosing to remove them.  You still count the amount of items you have, as a whole.  However, you are allowed to pick which ones get removed to satisfy the requirements of the event.

So, for example, you have six items in total and two of them have the "KEEP" status (the status we're talking about).  You get knocked out.  At this point, you have to choose three items to remove, because you have six items total.  Since you're the one that gets to choose, you would see three of these items go away and may choose one of the KEEP items to remove to fulfill the requirement.  This seems all by the rules at this point.

However, let's say you hold all of the KEEP items.  Now, you have two KEEP items and one other item.  Let's say you keep going and find another KEEP item.  You now have three KEEP items and one normal item.  You go mad now, for whatever reason.  At this point, your total is calculated again.  Four total items mean that you have to remove two items from your inventory.  The logic of the board dicates that either you, as the player, decide to remove two items of your own or it forces you to remove two items.  You can still choose, if you wish, to remove a KEEP item to satisfy the request.  However, since you cannot be forced to remove these items, you can instead have the logic of the board remove your one normal item.  Once it's done that, the board would then need another item...but since all the rest of your items are KEEP items, it fails to take any more items from you.  Thus, you are now able to keep all of your items.

That is the basic way the rule works in terms of the knocked out or insane status.