MAP can hide from the body's immune system- within a part of the immune system (joggin my memory now)- also MAP does not have a regular cell wall like other bacteria (why called clear bacteria)
True, this is MAP's way of escaping being killed by the immune system. There is a continuing war of innovation by bugs (just as with human weapons of war) and response by the immune sytem, and sometimes the bugs get the upper hand, which is why we need antibiotics. However, the immune system is still aroused by the bugs, causing inflammation; it is not "stupid" enough to get aroused by nothing. The old fogies in the medical establishment want you to believe this is due to some peculiar weakness in the victims, or to "stress," or some other mysterious cause.
Conventional therapy for possibly infectious "auto-immune" diseases involves deliberately weakening the immune system with things like methotrexate, sulfasalazine, etc., always with side effects, which may be disastrous.
IIRC, regular TB become ingested by macrophages, but for whatever reason, the macrophage's enzymes are unable to digest the bacterium.