I disagree.
I think it may be a Republican and they are sitting on it until he either becomes the RNC nominee or gets a solid #1 position in the polls. That way, the LAT hopes it will be too late for the Republicans to regroup.
The problem if something's really juicy (which this allegedly is) is that a truly compromised Republican candidate could withdraw and someone stronger take the reins. As widely known as this scandal apparently is, someone who doesn't believe in 'last minute gotcha' reporting will leak it to Drudge. The circle is too big for a long term tight hold without massive pressure. To my mind, that leans to be a Democrat whom they wish to protect. Only if it were something that would never see the light of day, could people's competitive juices be calmed enough not to jump the gun.