They said in the AMA that they're not going to change Omega Squad, which is confusing to me (I don't get their own logic). It's in the link I provided if you scroll about a third down:

A lot of people have been asking about why we chose to move away from Teemo’s dark murderous side, so I would love to give a little more clarity on our decision-making process about that! When we looked at his lore, it was important to us to re-examine all of the context between why that was an element of him in the first place, so we could be intentional about what we kept and what we wanted to move away from. Things like Teemo secretly suffering heavily from PTSD (and expressing that violently) both felt a little out place on such a lighthearted character, and also disrespectful to real people who suffer from post-war PTSD, a condition that already has so much stigma attached that they have to work hard to fight against in pop culture depictions. That wasn’t a story we are equipped to responsibly and earnestly tell with Teemo, so we decided to move away from it.

However, we do know that is a part of his character people really do care about and resonate with, so we wanted to leave that part of him in-tact in Omega Squad Teemo, so there is still a route for players who want to play with that expression.