I doubt Thai does any passport verification pre-flight. I've had old passport information saved in multiple airline websites. What matters is that you present a valid passport at check-in. Surely more than just a few passengers have made typos when entering their passport information, considering how many tickets they sell. Your typo might just be only in the year field and off by one year if you catch my drift. Such a typo would allow you to complete the purchase on the Thai website. But as others have noted, if you want to 100% rule out any issues purchase from a third party that doesn't require your passport information.