A follow-up question: Do they then transform from Skroxigor unit into a Kroxigor unit? With this I mean, do they have and near-by units have to take a Panic test for an annihilated friendly unit as is the case with a unit that contains hero/lord and all but the character are killed? It's hard to explain, please ask if you don't have a clue what I'm talking about and I'll try harder.
Skrox units are skink units with a krox upgrade. They always remain skink units, and will regain skinks if healed (after any krox due to multiwound preference rule satisfied), even if there are no skinks currently in unit. Krox do not lose stomp while in skrox units, just are unable to utilise it while skinks in way, if no skinks in way no problem stomping as normal.