From the DT FB Fan Page:

Koshka, piloting Gran'ma, activate together and perform the first of a Move+Move. A Ludwig destroys Gran'ma via Reactive Fire between the Move+Move activation. Koshka ejects. Can Koshka now continue with the activation and make a second Move as planned?

No, Koshka is a separate unit and for all intents and purposes counts as a carried unit in the walker and follows the transport rules for when a walker is destroyed. additional since piloting a walker also uses the pilots activation for the turn you will not be able to activate the pilot until the next turn or a command squad reactivation.

Good eye, Dakkon. I neglected to assimilate the carry capacity rules with the pilot rules, looking into the whole activating together + pilot doesn't add to the capacity of carriers.

Just making easy rules unnecessarily harder.

*as in I am making the rules harder