This is entirely speculation on my part. I don't think the 66mm was really unique to the telescope, and in fact, my guess would be that it was simply the same lens that Kowa (and others) uses in its spotting scope.
For every 66mm telescope sold in the world there were probably a dozen 66mm spotting scopes.
When the contracts for the 66mm spotter were filled, the machines were re-programmed to spit out whatever design was next on the contract fulfillment workload.
If the spotting scopes all sell out and another order is made, then whoever bought lenses from that run to make telescopes will look at their sales and decide if they want to buy more lenses.
It is a lot cheaper to piggyback off of a large contract order than to go in and say you want 200 of something. The guy that wants 2000 gets a far better price and if they are already going to make 2000 of something and you know the company, they will probable give you the same rate if you buy a couple of hundred.
That is my guess as to what happened. Business happened. I was in business for 35 years and this is the kind of thing that was probably at play here. Again, speculation on my part, but that is how business works. The people that make the lenses want to get as much production on the order as possible and when that order is done, everything is geared to make the next design for the next customer.