I'm pretty certain this functionality was intentional, though the work-around is certainly undesirable. Instead, I think, if fraud checks can be skipped for existing customers, it should only be possible if the customer has active services, or previously approved orders.
A setting in the order plugin along the lines of:
[x] Run fraud checks for all orders [ ] Run fraud checks for new customers only
Might work... and if you opt to run checks for new customers only, then they would have to meet criteria mentioned above (existing approved orders, active services)
Thoughts?