You focusing on the tree and losing the forest.
I can list you all the abilities and doctrinal abilities conscripts get and only riflemen would come near the number of things available to them. (and that because of the USF design)
The bottom line is the have too much utility compared to Penals so Penal do not look cost efficient by comparison.
If you read more carefully you will see that the suggestion is no tech cost for AT grenades, so imo soviet actually get buffed not nerfed...
AT grenades is 125 25
T1 is 160 10
the 15 Fuel less to have access to AT grenades is is more important than 35 Manpower...add the access to other units and the CP gain and it will feel more like a buff than an nerf.
Once more those are details, pls lets try focus on the direction and not the details.
conscript: merge, molly, at nade, sprint, trip mine, sandbag(6). (doc: ) ppsh, hit the dirt, PTRS, Ant-tank barrage, anti-tank mine, repair, FHQ, motherland(8). total: 14
grenadier: riflenade, faust, medical kit, lmg, bunker(5). (doc: ) g43, cloak, interrogation, hulldown, stun nade, sprint, tactical movement, counterattack tactic (8). 13 ability
the conscript have one more ability than the grenadier, two if you consider tactical movement and sprint on the grenadier to be the same abilities. In addition, the grenadier's non-doctrinal abilities are significantly better than what the conscript get as well. Riflenade, lmg42, and faust is an incredible combination.
The conscript might have more varied abilities from doctrine, but they are still doctrinal. The grenadier's superior abilities mean they are not dependent on having the right doctrine.
there's also a difference between paying an upgrade to grant an abilities to your infantry versus needing to buy another infantry for the abilities.
it's not just 160 mp 10 fuel, it's 160 mp 10 fuel + the cost of the unit itself.