Which means it have ever harder time hitting anything, thank you for contributing positively for the IS-2 being weak against infantry.
Nope, not really.
Squad dispersal is incidental. Its a problem overall in CoH2. Sometimes they clump, sometimes they dont.
A 6man unit has a wider dispersal, so though there is a marginally greater chance a shot will hit a model, it also means it can hit it in the periphery of the larger, wider unit dispersal, causing dmg to less models than in a 4man unit where it is less dispersed and more likely to take a hit to the central grouping.
IS2 also has 0.5 greater AoE radius, which is substantial in terms of hitting more models on a smaller unit, the line width of which is less than on a 6man unit, where it might wing it for a model kill on the edges, but "waste" the rest of its AoE to either side.
Scatter, necessarily, is greater on IS2 for this reason, or it would wipe 4mans far more consistently.
Thanks for the comment on positive contribution though
Maybe one day someone might say the same to you, though it hasnt happened yet!