I can fully see the government hiring on an individual basis. Saying that the government hired the guild spesifically makes it seem as though they are some sort of A-team crack group of soldiers which was sought out by the government. Five men enter the employ of the government and form a guild together. Fine. The government hires a guild of mercenaries. Hm, doesn't sit quite as well. Makes the group seem exclusive. As though the government needed help and sought them out rather than just saying 'mercenaries wanted, sign up here', which seems to me to be what they'd do. Also, something bad about the OP's brain, jut for that wonderful thing called balance.