I've seen a scheme mooted whereby the prospective student buys a share in an aircraft that doesn't comply, to enable them to learn under the rule that says you can learn on your own aircraft. In this case, the calendar and TBO requirements don't apply. I think for a person new to aviation, they are being led a bit into at best a 'grey area' of risk. i think they would need to have the differences and implications explained to them in a thorough and transparent manner.
The tone of the latter part of the OP's post seems to suggest that they feel that the manufacturer's recommendations are specious. They might say that after a certain period, their product is no longer 'perfectly good' and carries an increasing risk of failure. Lycoming engines are particularly susceptible to failure if left for a period without operating, hence the calendar restriction.
You CAN carry out ab initio instruction on an 'on condition' engine, but not in a 'commercial' setting.
TOO