Why Does Viktor's Ultimate Not Count As DoT Towards Rylai's?

After the buffs ( that were probably supposed to be nerfs ) to Viktor's Ultimate, for most champions that do not have a dash or something simular it is practically impossible to run away from a Viktor ultimate with Rylai's. On top of most likely taking the whole damage of the ultimate this also means that they will be permanently slowed for 40% while they are in there.

And this is really weird. Look at this: http://leagueoflegends.wikia.com/wiki/Rylai's_Crystal_Scepter If you look at the description you can clearly see that DoTs should only slow for 20% rather than 40% for 1 second. Sure, Viktor's Ultimate ticks very slowly but it is still a DoT in my opinion.

What I really don't get is why this hasn't been noticed yet. When Singed's Q applied a 40% slow instead of the 20% slow it should've it got fixed instantly the next patch. And it's not like Singed has been a dangerous threat to the game balance anyway.

If anyone from the balancing team sees this I'd like to ask you to hotfix or implement the change in the next patch notes. There have also been people on the Internet saying that there are other cases of Rylai's either applying a weaker or a stronger slow than it should but I can't confirm these on my own.

I will post this in Gameplay rather than Report a Bug because I don't know if this is actually intended or not.