The rate of climb of the MSX in the last 1000 ft is most probably why RAs were triggered I would say . So far normal, but why the MSX continued to climb above its cleared level, against the initial RA to level off, and were they subsequent corrective RAs issued and to who, will the interesting bit, hence the investigation . Could be pilot over-reaction (most likely) or a TCAS bug.. will not be the first time . Curious of the result.