Bill Catchings (the undergrad who helped Frank da Cruz with the original spec and coding) still blogs. It has been a while since he spoke specifically about kermit, but he has one or two interesting posts about the 40th anniversary of Kermit.

https://www.billcatchings.com/2012/04/frog-from-my-past.html https://www.billcatchings.com/2013/11/kermit-oral-history-pa...

and here is a link to the oral history he discusses:

https://www.computerhistory.org/collections/catalog/10274641...