Agent instructed him not to discuss contract terms?

Have a 27 year old striker in on loan with an option to buy, and when I offer him a contract his agent has instructed him not to discuss contract terms until I offer a contract. What's the point of such a tactic in negotiations?

Fine. I offer the default, and not only is he insulted by the low pay, he also says the contract length is not suitable at this stage of his career on 3, 4, and 5 year contracts. I surely can't offer a big signing bonus on a short contract...