In general yes, if the protein works as a good drug the matter of synthesising it is a solvable engineering problem.
However we are not talking about a pill. We are talking about a daily injection. We are also not talking about completely reversing all aging but some aspects while likely suffering side effects.
Given the priors in a case like this, it's unlikely that everyone will soon take daily injections of the protein.
In experiments performed on mice, blood transfusions from young mice reversed age-related markers in older mice. The protein involved is identical in humans.
http://mic.com/articles/88851/harvard-scientists-may-have-just-unlocked-the-secret-to-staying-young-forever