I wouldn't worry too much. UMass' Computer Science program is ranked very highly - comparable to Ivy League institutions. It's also the flagship public university in a state where higher ed is very, very important. Talking to Boston-area CS profs, I've heard that UMass is better than, say, Harvard for PhD students because the support provided to students is better.
In a financial crunch things can get uncomfortable, but UMass Amherst probably qualifies as too big to fail. And administrators are less likely to damage nationally-ranked departments then weaker parts of the university. For instance, after Katrina, Tulane killed off its CS and engineering departments (including civil engineering!) but kept areas where it was nationally ranked.