I can see the issue being identified, the unblock function will be required before customer history can be viewed.
To view booking history for blocked customers you can always input their details in the search box, I appreciate that the problem is when the booking process is started it is not practical to search in this way.
We can maybe look at ways to display customers who are blocked with some booking history notes to elaborate on the reason for their blocked status.
If we do update this function in any way I will let you know.
When booking a guest who is blocked it comes up with the box saying that guest is blocked and would you like to unblock. Would be helpful if it also had the information that lead to the person being blocked, when it booking stage its hard to stop the booking process or inform the guest when you have guest on the phone you can only unblock and then discover. Ultimately your not going to refuse to take a booking but if its someone that does have a history of no show it would be good to know before unblocking.