I think it is a good tactical decision for IIM Rohtak to improve its worth and image among the second-generation IIMs.
Despite being younger than IIM Shillong it is considered among the second-generation IIMs because it has been a part of CAP. If you look at the current situation, IIM Shillong functions from a temporary campus and yet has its own WAT-PI process. On the other hand, IIM Rohtak has its own permanent campus but lacks its own WAT-PI process. Now its withdrawal from CAP will enable it to stand out from the second-generation IIMs.
From the student's perspective, this strategy has increased their chances of getting selected as now if they fail to perform well in CAP, they can rely on Rohtak's own WAT-PI process and vice-versa.