You probably never worked professionally trading options but if OCC made any execution decisions then they wound also execute OTC options and they definitely don't because if you don't give notice then your OTC option expires worthless, in or out of the money (there are actually quite a few stories how large sell side banks' middle and back offices failed to issue an execution notice and their itm options expired worthless). OCC and other international clearing houses settle contracts per instructions from their clearing members. OCC started to settle spx index OTC options in 2013 or 2014 if I recall correctly and take instructions from what they call "approved OTC trade source".
In the same manner they settle listed options and take instructions from the listing exchanges.
In the same manner they settle listed options and take instructions from the listing exchanges.
Yeah, m'kay. You know better than brokers and the OCC itself do. Good luck with all that.