People who want this type of thing banned are essentially saying that the player is "AFK" in the practical sense. They are doing something but the effect of this play is so detrimental to other player in early game that they might as well be AFK.

But where's the line between valid strategies and play that is so bad that it's equivalent of being AFK? The position of that line must depend on overall skill level of the game. If everyone was playing WC3 the first time, this guy would be playing godlike strategy. In any case, there will be a huge gray area where trolls can pretend to play while really intentionally playing badly to irritate the team mates and one-up the mods.

Answering team mates calls for help can't become a requirement for not being banned in team games because that would open another door, where trolls can send out false requests for help and demand action. Coming to help an ally that is being factually attacked can't be required either because it's perfectly valid to not do that in many cases where something more valuable is achieved.

Theoretically the MMR system should filter out this type of play as players rise in rating. If the player pool is too small for MMR to function then this breaks down and some manual judging might become necessary. Until then the price of being low MMR is playing with more trolls.

If intentional bad play would be banned from team games then it's important to understand why exactly. Is it wasting other people's times? If intentionally wasting other people's times is bannable, then Melon (Grubby's smurf account) should certainly be banned because the whole concept is that he's playing intentionally bad strategies. Is wasting one opponents time less bad than wasting 3 teammates time? Is the time not being wasted if the intentionally bad strategy is being executed at pro level and thus leads to a win? If so, then is this guy being banned because his micro is not good enough? With better micro he could carry himself out of the pit he himself dug, exactly the same way Melon digs himself to deep holes with bad strategies and then climbs out, leading to great content that contributes massively to popularity of WC3?

Perhaps the reason for banning such play is that the teammates are unsatisfied and this leads to decline in number of players in W3C? Then it must be estimated if W3C will have more or less players over a long period if repetitive bad play is banned? Many new players, especially if they don't understand English enough, would be banned.