It's a known glitch. From the UESP:
Do be extra careful during the escort, do not under any circumstances talk to an ordinator until you have safely brought Entius to Frald the White. If you insist on talking to an ordinator while Saprius Entius is following, they will automatically attack you. But that's not all, from now on any ordinator in Vivec will automatically attack you on sight!
If you caught this glitch, you can fix this on PC by first finding a wandering ordinator, then before you are noticed by that ordinator, bring up the console, click the ordinator, and type setfight 10. Now this particular ordinator should not attack you (others still will, however). Then, proceed to commit a crime in front of this same ordinator, and pay it off or go to jail. Now ordinators should not attack you anymore.
Looks like a PC-only fix. (I assume there are mods out there that would also fix it).