From a online retailer perspective it makes perfect sense, from a buyer perspective it makes no sense. From a business owner perspective I'd be mad as hell. I worked retail both online and in store for many years...
If someone was in my shop and was told to go buy it online I would be raising hell, all you have to do is take the customer to the counter ask them what they'd like to buy, have the cashier buy it for them online you can keep a company credit card for those types of transactions and just add the small fee into the in store purchase amount so the inventory checks are all in place and nothing is screwed up.
All your inventory checks are done, the sale was done via the "internet" (in store) and the customer never had to hassle to do anything. If you want to succeed you have to adapt to things, but something as minor as this should never be a problem. In fact if done right the customer would never even know it went through the website but they'd still leave the store with the stock they wanted.
