We've been discussing this very thing (in my company) recently and for what it's worth came to the following conclusion.
The TCAS warns you of a "guaranteed" collision, imminently. The ground poses a threat, but it is subsequent to the anti-collision manoeuvre. The timescale may indeed be short, but we felt that the logical answer was to avoid the imminent threat first (i.e. follow the RA) and avoid the subsequent threat second. RAs clear the conflict quite quickly, which should allow time to pull up, even though MSA will have been "bust".