If I get an encouraging but noncommittal response from potential advisor, should I continue to pursue other potential advisors at this school?
It doesn't sound like he is just being kind. Using the wording "strongly encourage" is a good sign. Many US universities do not let individual professors have much of a say in a admissions and his response may be a reflection of that. 

Furthermore, many professors are not willing to commit to advising any students before they have been accepted. It sounds like this professor wants you to apply and would be open to talking more if you are accepted (or are visiting).

You can continue to look for advisers, but I'd imagine most of them will say the same thing. It's never a bad idea to see what else is out there, but it's hard for many professors to say much this early in the process.