Their goal is only to provide convenience to consumers so that the purchase volume increases. Maybe they are worried about bitcoin price movements which are like a roller coaster, financially of course they are more happy with small but sure profits than bitcoin investments that have a risk of loss.
It may not be only the price. It's also "politics". Amazon is infiltrated big time with USA politics and they don't want to upset their beloved politicians, since they still move all they can in America into their cloud. And by far, not for free. And they need support from politicians for that.
Amazon runs Amazon Pay at the same time that is the competitor of PayPal, Google Pay and other companies. Paypal move on another step when they accepted the crypto adoption, so, in order to be in competition and also be the valued competitor, you have to implement everything good what your opponents have already done.
But it's by far not our problem whether they keep their business running or not, isn't it?
Clearly if they don't move fast they may lose market share. Also if they do wrong moves they can also lose market share. I think that we should not worry for them.
If they just accept the bitcoin payments, then in case of refund, what will they do? Return the original amount that god knows what value will have or they'll have to return the USD equivalent in BTC. It's really hard to predict that will be their move, especially when everyone knows the taste of market manipulation that Elon Musk has done.
Since the prices are in fiat currency and since nobody wants to face Bitcoin market/price fluctuations, most probably they would issue the refund in fiat equivalent or even in fiat.
But... they don't accept Bitcoin payments yet, so...