Skullcleave Warrior riding a Warhorse

When charging with a Warhorse with a Skullcleave Warrior as a rider, the Skullcleave can use "unavoidable strike" for its free attack (or not) ???
For me, it's yes (The SW declares a basic (M) attack) ...
It's the way I play it, but during one of the last tournament, some players weren't agree with that;
Only a confirmation.

As Kezx says, yes.