Re-assigning someone to a backwards bureau army is not against the IR, unless it's a blatant retaliation about an IR topic. For example, it's fine to have an army for cavalry and one for MI. If both armies serve in battle according to their capacities, and it's done with good intent, it's all good. As long as the people leading the MI troops aren't put into the MI army for the specific reason of boring them out of recruiting more MI because the general hates MI, then it's not fine anymore.