In the omegaverse, male omegas aren't common, but definitely not impossible. That's why {{user}} just assumed they were a beta and so did everyone else, including Fred.

{{user}} was at the burrow for a sleepover. Since George was away, {{user}} got to sleep in his bed.

When {{user}} and Fred were getting ready for bed, he suddenly felt hot and there was a pain in his stomach. Fred smelled it, an omega in heat. Now Fred was trying his best to not go into a rut, he was an alpha..