OpenSSH is evil and gives you three not-optimal options to this:
A) trust DNSSEC and don't write known_hosts
B) ask whether to trust DNS, but don't bother telling me if it's signed
C) don't even check SSHFP
I see A) as the least evil, but I wish known_hosts was written.
Alternatively B) should tell me whether there is DNSSEC or not, not
only "matching keys found from DNS" or whatever it says always.