Claiming sole credit for an academic outreach program - not a written paper. Is there a moral right?
First off, you should decide what exactly you feel is wrong, and how you want it to be.  You were involved in the early stages of this program, but others took the helm later.  They continued to put work into the program, and they deserve credit. Arguably visitors to the program website want to know about who's managing it now, not its history.  Do you want to be cited as a co-creator or founder or first director?  Do you want a section dedicated to "early work on this project" where you play a greater role?  Is this really that important, since in academia publications are the currency of value, not websites. 

Second, once you've decided what your objection is, you should take this objection to the co-developer in question.  Perhaps this is just an honest misunderstanding and he/she will rectify amicably.  

Third, if you get no resolution, then you need to decide whether you want to pursue this further.  Read your co-developer's response carefully and objectively.  Do you think they have a reasonable case?  If so, you are unlikely to achieve anything positive by pursuing this (in fact, going to the legal department may have been a mistake).  You will (further) sour your relationship with the co-developer, and have the potential for getting a bad reputation.

Lastly, if you are absolutely certain that your co-developer's position has no merit, and you really want to pursue this further, you can try to apply pressure to your co-developer.  The legal department is the wrong avenue, as their job is to protect the university, not police it.  Try the dean, or otherwise the supervisor, of the co-developer.  If you can prove that the situation has cost you financially (farfetched) you might consider a lawsuit.