Just sounds to me like a disgruntled seller that has been stuffed around by buyers one time too many.

Whilst not the approach I, or many other sellers, would adopt, I certainly would not poke fun at the misfortune of others to have been pushed to add such terms and conditions to their descriptions.

Given that an increasing number of buyers don't seem to bother to read descriptions as eBay has buried these on the mobile app (and the proportion of buyers using their mobile to purchase is only increasing) ... 

I am truly not sure that it even matters what a seller puts in their terms and conditions and that they would lose much business anyway TBH.