I might be missing something, but it seems you're making some unwarranted assumption there. Stripe guarantees a $101 quote to the merchant. That is, as long as

I might be missing something, but it seems you're making some unwarranted assumption there. Stripe guarantees a $101 quote to the merchant. That is, as long as the consumer pays 1 BTC within 10 minutes, the merchant will get $101 -- essentially Stripe buys BTC at $101. But Stripe is not selling BTC at $101! So even if the bitcoin price goes down 5 minutes later so that Stripe promises to buy at $100 (for new orders), it's not necessarily true that the consumer can buy at $100.