Just as every politician has a certain amount of political capital, they all have a certain amount of lying capital. Spend too much and people will begin to think you have a credibility problem and won't believe you. (See Bill Clinton.) And for Obama to spend it so frivolously, on something so unimportant, well...
He really is a spender, isn't he?
My hunch is that it's almost impossible to come up with something original with respect to politics so let's Google and find out:
"Bowgate" or variants: 15,000 hits
"It's not the bow" = 6 hits
"It's not the bow, it's the cover-up" = 1 hit (Kudos to a commenter named Bob Wang on this blog, great minds and all that)
"Liar's capital / lying capital" - 0 hits (Very awkward locution so not surprising that there's no hits; plus people don't want politicians to have lying capital)