If you space it on the left, you then need to space your caliper to meet the disc (with all the attendant problems of caliper tabs being loaded in a way they weren't designed for). If you space it on the right, you get a chainline of about 30mm. Basically a terrible idea if you want a 135mm hub, and not even easy to get either, unless you speak Polish. Are Mielec making a lot of 120mm disc frames? That might explain why Polish shops have that Novatec hub when nobody else does.
If you space it on the left, you then need to space your caliper to meet the disc (with all the attendant problems of caliper tabs being loaded in a way they weren't designed for). If you space it on the right, you get a chainline of about 30mm. Basically a terrible idea if you want a 135mm hub, and not even easy to get either, unless you speak Polish. Are Mielec making a lot of 120mm disc frames? That might explain why Polish shops have that Novatec hub when nobody else does.