I believe the path for Krebs when under DDOS was free CF cloud to akamai to special status (from Google?) Using CF domains with or without CF's normal services turned on would have made akamai impossible until a transfer process to a real registrar completed leading to an extra week or so of downtime.
That could be an argument not to use their DNS service and their CDN service.
It shouldn't be an issue for the DNS service by itself.