So for this militia unit, with all infantry having srms as their long range, scorpions with only an ac5 for reach, and only 4 warriors so not enough to provide any real support, the militia is missing indirect fire and munitions.
Your setup is going to rely heavily on infantry, with the ac5 tanks doing the line holding and breakthrough. Light mechs cant hold ground, but a company of locusts is one of the strongest non-jumping scouts in the 20 ton bug class. The LRM5 locust can provide LRM support, which your militia simply doesnt have and desperately needs to take advantage of all the infantry spotters. Probably 8 scout 1v locusts and 4 fire support M locusts.
After locusts help shore up your scout deficiencies, the next 20 ton bug mech id want is something with hands. Hands help a militia so much more then guns, and at 20 tons the ability to move 2 ton tank traps or earthworks around at incredible speed compared to loading and unloading a 2 ton truck load will mean you can create all kinds of on the spot fortifications. You can also uproot trees to build walls and such. The only 20 ton bug mech with hands is the stinger, so a company of those. The jump jets also let you mountain range for ambushing conventional or what not. And they can scout too, helping the locusts and warriors.
Finally, the faction specific. To fully metagame it, Id want something as heavy as possible, so the Lyran Wolfhound or Kurita Jenner F. But the Davion Valkyrie has LRMs, which as mentioned your militia is super short on indirect fire weapons. The davion Javelin also has an LRM15 variant. So Davion is winning due simply for having access to the most LRM signature mechs available. LRMs let you engage with your limited mech forces at an arms reach or totally out of reach in the case of indirect, and return home. This should preserve your mech force for as long as possible, and while a company of wolfhounds can spearhead a counter attack, they will be spent rather quickly on the attack and dont do well in static defense. Valkyries and LRM Javelins will probably take place in 3x as many fights if not more as they appear, fire off all their LRMs, and retreat for resupply without needing much in the way of downtime to fix armor damage.