@Jan10926 Inquiries (as opposed to Requests) do not require that you either pre-appprove nor decline. All you need to do is messsage the guest back within 24 hours.
I would message back saying, "No, XX, that is not correct. I require that guests have a profile photo in order to consider accepting a booking. Airbnb is a system built on trust and openness between hosts and guests. An anonymous grey sillouette does not inspire confidence. A guest who has just joined, has no reviews and hasn't bothered to fill out any profile info is not likely to have a booking accepted. "
Then just leave it. You may get a response or never hear from them again.