The excuse for asking is the post itself. The following players have documents, find out what they want to get them.
I think it's pretty clear players are encouraged to find NPCs and actively try to gain spell docs. They don't need an excuse. No....you don't have to have a quest. Yes, you ought to be cooperative in giving players a way to earn them....or at least a way to contact you.
I know you Ren, are giving players a chance to earn the docs. Some though, are simply evasive, and rude when asked. If as an RPC you don't want to deal with this...maybe another RPC should hold the document.