uhh...
Sion actually has the lowest base HP of his class, and in order to break even he needs at least 400 health from his passive.
Also, "inting sion" is just a meme used to garner views. Kamikaze sion is just a variant of the goon push build; you counter goon push with goon push.
Further, Kamikaze sion relies heavily on demolish to take towers fast enough to be a threat. CC him away from the tower or camp him early to delay his item spike.
If you leave him alone he splits like any other split pusher. I really dont understand why people cry so hard about it.