Varus Midlane glacial augment rune?

I just recently played with a varus mid main taking glacial augment as his primary rune. Does anyone have any experience with glacial augment or knows why this person takes this? The glacial proc only works on ult so why would you take it in laning phase? PTA, HoB and lethel tempo outshine this rune no?

Link to profile https://www.op.gg/summoners/euw/precomed-6969

Edit:

I played Varus/Kai'sa top 2 seasons ago and reached diamond 4 on 2 different accounts. My second question is, why would you play Varus midlane were there are a lot more unfavorable matchups compared to the toplane?