No, booking a ticket for someone else is not selling it. It is only selling if you are paid for the ticket you book.

What you can do is book the ticket using your miles and give the person the ticket. Then you can hope that the person will be so thankful that, in a completely separate transaction, will perhaps give you a gift or buy you something that might just happen to be valued about what you feel the miles are worth. Two separate transactions, hopefully days or weeks apart, with the express understanding that any payment by the other party is not paying for the ticket you obtained for them.