Unfortunately, answering/responding/replying to a message does not count as a response, @Jann3
The clock still ticking until you pre-approve/decline an inquiry or accept/decline a reservation request.
Not making a decision within 24hrs to an inquiry affect your response rate.
Not making a decision within 24hrs to a reservation request will result in having the dates requested blocked from the calendar.
An inquiry does not block your calendar while a reservation request does. As soon as you decline a reservation request, it opens up the dates again, and if you accept then the dates blocked because the reservation is now confirmed/accepted.