Whose fault is it if they accept a sub-optimal offer? It is the agents fault. The listing agent has a contract with the seller to present all offers, to market the property etc. If the agent did not fulfill his/her end of the contract, that’s unethical. Its even more unethical if the agent does not fulfill the contract for personal gain.
Yes we all have different ethical standards, so you have a right to say that my ethical standards are not yours.
So just say that, but don’t say that I’m hypocritical or that if I were the buyer I would think differently.
The fact remains that I would not think differently about this situation if I were the buyer.