Exactly. GAAP is irrelevant to Bitcoin. Unlike some currencies, Bitcoin isn't a debt-based, fractional-reserve, leveraged pseudo-money that requires fine-grained, exact time-based tracking in order to prevent fraudulent third-order effects (like that ever even worked, anyways; high-frequency Bitcoins here we come).
You don't need to pay taxes on Bitcoin transactions. In fact, you shouldn't. And you shouldn't try to use Bitcoin as a means of transferring value denominated in inherently flawed, poorly-accounted-for, debt-based, fractional-reserve, fraudulently-leveraged pseudo-monies, either.
That's pretty obviously what this request is about. And it's not even remotely in any Bitcoin users' interest to help make that possible.
In addition to this opinion (which I entirely agree with btw), is that none of these issues should be addressed by the ref.client - store the blockchain however you'd like to, mine it to calculate timestamps on transactions you're interested in. The vast majority of users don't need this functionality and probably don't even know why they don't want it.