Tax is based on destination. or where the item will be used as they say.
If he buys and has it shipped to you it should not be taxed.
Oh, the horror stories...i did our taxes for WA and ID which have entirely different ideas of what items should be taxed :/
$50,000 accounting system and $1000/month support and they were clueless. Very few systems handle SOMETIMES very well as an answer to TAXABLE?.... Don't even think about a normally nontaxable item (syringes or injectables ) that needs to be taxed (sold to vet instead of a people dr)
I think Amazon blew it. They admit they have a presence in TX if they say they have the power over it to remove it. Ooops, should have skipped that threat.