@Bulgakov
That "bad player" is 37th place in 1v1 sov with over 70% of wins.
Thank you for extremely accurately describing current german meta of 4 grens+MG or pure grenspam.
You know if something is actually over powered arguing based on rank is meaningless, right? An overpowered strategy will inflate their rank.
Anyways, I don't really think Maxim Spam is good enough to necessitate changes. Luvnest seemed like he was taken aback by the extreme nature of the enemy's strategy. He responded appropriately to maxims (building a Sniper early), but did not follow through with an additional sniper after he saw the depths of the opponent's commitment to Maxim spam.
There's no way that the opponent could have realistically held the cutoff outside of his base for so long against two snipers. Even one sniper was a huge threat. Having his cutoff would have bolstered his resources and he could have gotten new counters in Tier 2.
I think that the Mortar Halftrack was a bit of a mistake too. As people have said mortars seem to struggle against this sort of raw Maxim play. I think that Luvnest would have been better served with a 222 Scout Car and a Halftrack which costs 45 fuel (roughly the same).
Pair the 222 Scout Car up with a pioneer squad with mine sweepers and send them off to the fringes of the map to capture less traveled territories. For Langskaya this basically means the west. The 222 inflicts devastating damage to Maxims at close range. There's a natural worry with mines but that's why the capping unit that travels with the 222 SC is the trusty pioneer with sweepers. The mine detection radius is fairly large so you can at least be sure that your path to the maxim is safe. I mean, you can see it in this game! He uses the Scout car to help push maxims out of the west and then sweeps in to support his own forces. The mortar halftrack delayed this action and probably hurt him.
The 251 Halftrack is there to secure dropped maxims. Maxims are good as we can see! With two snipers and a 222 you can chase and kill Maxims early. Dropped maxims are usually a pain to recrew but the Halftrack helps with this. Once you have a Maxim it can be used to further solidify the line from which your Snipers operate. As others have suggested you can also use this for a point blank dropoff flank but this action is probably needlessly risky as it leaves your Snipers vulnerable and you could hit a mine. Options are always nice though.
The enemy has access to their ZiS guns to help deal with T2 armor but Snipers are pretty good at disrupting these too. Just keep them a little back and let your Grens screen.
When you're facing flat out maxim spam like this you need to realize that the enemy's throwing away a long term advantage for a short one. Maxims are utterly useless against armor unlike other basic units. They have no AT grenade. They have nothing. In the later stages of the game they will suffer as the battlefield changes. The biggest question is if the early game advantage is enough to counteract this. If Maxim spam is re-surging then people will learn the tell-tale signs and being using appropriate counters like Snipers.