What does that imply? What if it costs more to ship items than to sell them in their stores?
You expect people who shop in stores to subsidize those who shop online? Much of Costco’s value proposition is they don’t waste time with packaging and so everything is designed to be taken off the pallet by the customer.
If they now have to package and ship bulky items, it’s plausible it costs more to do that. Or maybe they’re just price discriminating. Either way, they have no obligation to provide the same prices online and offline, or even between their stores in HCOL vs LCOL areas.