Exactly my point, expecting Penal to carry the T1 build on their own is bad design.
Yes, but comparing them to Panzerfusiliers without any sidenote is misleading, since those don't need to carry their complete faction. They are backed up by MGs, ATGs and a stronger early game Volksgrenadier to mitigate their early weakness.
And bad design or not, we will likely have to live with it since changing Soviet T1 is not just a slight tweak but a complete faction rework. And this we won't get unless Relic decides to be genourous and allows another big faction patch. Therefore, we have to make the best out of this and take into account that Penals need to carry their T1.
But back to OPs suggestion:
I agree that PPShs on Penals are highly unattractive. A different upgrade path would be nice, but I am not sure what would be the best. PPShs clash with Shocks, DP28 potentially with Guards. A bar-like DP28 would be a bit weird in the game logic since only elites can usually shoot MGs on the move. A Pathfinder-like sniper rifle could lead to a terminator squad given Penals decent DPS. Plus it clashes with the sniper in T1. That's a tough nut.
But what if this crate just gave Penals some utility upgrade? Would also be weird logic wise, but it's maybe a way to go.