Nah. Mark went away, so we can talk about this like intelligent people acting in good faith.
The reserve is statutorially full. The president, by law, may not buy any more. But it's not actually full (in fact, even when it is "full" it's not "full full" because it has physical storage capacity of somewhere in the 725 mm bbl area, as Tricky said. But we can safely ignore that for now).
Specifically, there's about 12 mm barrels of product out on loan. Those loans were to refiners and oil companies and pipeline companies to mitigate the disruption caused by Katrina and Rita.
What's the difference? The loans are of barrels, not dollars. So the 12 mm bbls which are to be replaced are not subject to price risk.
What the president ordered is that the repayment of 10 mm of those 12 mm barrels be delayed until the fall. He did this at exactly the same time he waived some of the federal gas-mixing rules which were scheduled to be mandatory tomorrow because of a feared shortage of ethanol. Because Congress (and the President) failed to pass an MTBE liability protection package last fall, no one will take gas with MTBE this year. That's the equilivent of taking three small or one mega refiner off the market.
So what we've got is domestic-based supply disruptions caused by two identifiable, short-term reasons. First is the lag of building ethanol plants to replace the lost MTBE (which the remaining producers are now exporting(!)) and getting it to market (another meaty discussion which I'll defer unless anyone cares). Second is the ongoing reduction of capacity in the refinery business because of the aftermath of Katrina and Rita. The industry is only running at ~89% of capacity because of outages, whereas at this time of the season they're normally going full out and when margins are this high they would normall be going more than full out.
The purpose of the SPR, besides providing during times of war, is precisely to mitigate these kinds of short-term, non-price-based supply disruptions. It absolutely makes sense to defer those loan paybacks. Not because it can reasonably be expected to lower prices (though there seems to have been at least a modest psychological effect) but because it can reasonably be expected to mitigate shortages; i.e. no gas available at any price.