I've seen clauses like this in the past, but in reality there's no real way to enforce it. Also, builders don't make it a habit to stay in touch with buyers after close of escrow, so unless they have an army of cheap labor tracking listings/sales of their properties built within the last 2 years, there's little chance anything like this will stick.
The only real reason a 2-year clause applies to a sale is to avoid short term real estate gains taxes, where you get the $200k exemption after 2 years, but this has zero to do with the builder.