@faflec
Put another way:
Imagine an alternate universe in which ISC does not think their score is secure, particularly against a known top-scoring team. They get placed in the same Red Team, and it is fairly certain that this is the last scoreable event. They have the means to ensure they get another +185 points advantage over the team they're not sure they are beating.
The only reason they even have to consider not screwing the other team is that Mist (a group that has been opposing their progress from the start) has put them together.
They have made no declarations that they will support their current team, though a possible assumption is that they will.
I would not consider it a betrayal for that ISC team to defect against their scratch team. It is the logical move in their situation.
Similarly, in the real fictional universe, ISC defecting against their scratch team is one of many possible logical moves, not betraying any agreements that ISC has entered into. On the other hand, leaving a top scoring team without the additional malus makes it explicitly less likely to achieve the stated end-goals in an agreement that ISC did make.