Is it?
Let's extend that logic. That guy didn't do anything that Burk couldn't do. By Occam's razor then Burk is not an anomaly but same as him. Burk therefore is magic user. And that's not correct.
Like falling from the sky and not being harmed? Or using a log as an improv projectile and punching Pirate of the Storm like a ****ing truck?
That's speculation. Lina arrived with many magic teachers any one of them could cast that magic. I'm not ruling it out, but it could just be a PE teacher for mages.
He really went on a limb there.