My thoughts on Lotus having patent rights would be that they were owned by GM at the time the LT5 was developed. I got the impression from Mr. McLellan's talk that as soon as Mercury Marine was making production motors Lotus started making the next gen LT5 "prototype" motor for testing....which would mean that it belonged to GM.
The thing that always amazes me about the LT5 is how quickly the motor went from an idea to a motor legal for use in a production car. Them guys were burning some serious midnite oil! Heck the LSx development started around the same time conceptually. I'm sure Mr. McLellan mentioned at the BBQ that by 90 or 91 it wasn't available to use in C5 test cars yet because I remember him saying that there were two chassis test cars. The LT5 one, and the other had an L98 in it. They used an L98 because the motor dimensions were almost the same as what was going to be the LSx.
I will add this as it is just my impression from listening to Mr. McLellan's talk at the BBQ. He wanted the next gen LT5 before the LSx was even out of prototyping so he could have it for the C5. I mean his crew designed the C5. I got to say that this is just my speculation. He never said this at the BBQ, but if you were there and were watching him while listening to him...well I got the impression that the new LT5 & the C5 was the direction he wanted corvette to go in for the future. JMHO.
Just as a fwiw. His book, "Corvette from the Inside", is worth reading along side the HOTB....it kind of gives a more complete picture of not just our cars, but the engineering philosophy that makes the corvette.
Tom