Well, then again the Chief drug Blue Team with him when he initially went AWOL at the end of The Next 48 Hours story arc. He could be keeping them in the dark. Also, it would give 343i an excuse to implement something similar to Noble Team from Reach, or the various co-op characters in 3. We've already seen that Locke has 3 other Spartans with him in the H2A cutscenes.