Do you know what Aegis timing means?! That movement was textbook execution!!
Magnus BKB'd through and picked up the Aegis while Rubick was still in the cast animation. The reaction window plus distance read โ that's not something you just see and understand.
You said his performance was average? His GPM was 680 because he was sacrificing farm to enable the team's push timing. That's called a support sacrifice, not an inefficient game. Go check his teamfight participation on dotabuff before forming that opinion.