As long as you have evidence that the buyer sent a courier to collect, and you ensure that the courier does not take anything away until you have successfully uploaded the collection code, you should be safe.
Ebay assume that the buyer will collect a collection only item and they are not covered by the Money Back Guarantee if they send a courier,
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)