Erik already had to constantly move to avoid the invisible hands released by Bill, but at the same time also had to resist the elementalist powers. He was using wind to make it harder for Erik to move.
That meant Erik had to spend significantly more stamina than usual, forcing his wings to beat with greater force and frequency to overcome the opposing wind currents.
Erik had two alternatives here, two that would drain his mana faster. Either he could make flying easier by using telekinesis or create wind of his own to contrast that of the Elementalist.
He chose the second. The higher number of neural links made mana consumption lower, despite not being as effective as the first was.
Besides, Erik had to prevent the flames from spreading toward the plane.