Two reasons.
First- Lizard lines give the climb attribute which reduces damage from falls that result from flinching. The size 4 plateau terrain being fought across would result in a 4" fall. That's d10 damage for models without climb and d6 for models with the lizard lines.
Second- We gave the LAMI and SICON Agents lizard lines as part of the scenario, since they did not have jump packs like PAMI and it made sense.