What I suggested to jl777 in a PM, is that he make it (the coin age, a.k.a. "Coin Days Destroyed") a user-adjustable variable so that users can select the tradeoff between delay for themselves and those counter-parties available to trade with, and depending on the level of jamming present at that time. jl777 referred to it as a "rainy day" insurance, which seems an apt characterization of the suggestion.

I have my strong intuitive (generative essence) sense that I will find a flaw in any method of using a fee to block the attacker who wants to jam the protocol, because the fee can't be atomic with the trade (without also opening a jamming window of interaction), so a window of jamming is always opened. Whereas, the coin age is a finite resource which exists (is committed to) prior to the initiation of any protocol for trading. Also it is impossible to use a mixer to hide the identity of the attacker, since mixing will bump the coin age back to 0.

Note my suggestion hinges on the first interaction with the counter-party in the protocol must bump the coin age to 0 on the block chain (else only a local blacklist can be maintained which is much less robust defense). Otherwise the attacker can reuse the same resource over and over to jam with.

Jamming is the main obstacle I forsee impinging on the viability of TierNolan's decentralized exchange protocol. The next obstacle is the very limited scalability of transaction rate for existing block chains, but that is a holistic problem for crypto right now (meaning it MUST be solved else the crypto currency phenomenon dies).