@Annie506 You say you were asked to preapprove, which means this was an Inquiry, rather than a Request. Declines count against you on Acceptance rate, so you shouldn't have declined. On an Inquiry, all you have to do is message back, you don't have to Pre-approve or Decline and you can ignore those prodding messages from Airbnb.
So I would have just messaged back, as you did, telling her that it's inappropriate to use a host inquiry to drum up business for herself.
And like @Corliss2 suggested, you could have Pre-approved, it's not like she was going to book anyway.
I'd also report her to Airbnb. Tell them she's making fraudulent booking inquiries for the purpose of advertising her massage business.