So Why Does Sion...
Have a better version of Olaf's ultimate? Both become immune to CC, except Sion also gets a MS boost, and knocks up whatever he hits. #BuffOlafS5

Have a better version of Olaf's ultimate? Both become immune to CC, except Sion also gets a MS boost, and knocks up whatever he hits. #BuffOlafS5

Once he uses his knockup he loses his CC immunity. Olaf can attack for the duration.
already has a better version of Olaf's ult as a basic ability, so this is kind of pointless.
I have to agree with what someone else posted. Olaf has control while he's ulting. Sion can walk forward and kinda steer a little, but Olaf has so many more choices than Sion while he's ulting.
They're such different abilities that it's almost ridiculous to compare them.