He wasn't depicting Obama as an underdog. He was illustrating that Obama has had multiple well-funded opponents during his campaign that presumably had access to a wellspring of opposition research available on Obama. And, none of those opponents voiced ANY concerns, let alone substantive concerns about Obama's eligibility based on facts, not conjecture and supposition.
That fact, added to the absolute absence of any evidence presented by Orly in her pleading speaks volumes about the merits of this case, or so this court (and several others) found.
The citation by land of the campaign opposition war-chests had nothing to do with Obama has an "underdog". You should read the decision.
Additionally, during the campaign, McCain went out of his way to tell a woman at a rally that Obama was a citizen. Quite a risk to take if he wasn't sure.
McCain Supporter: "Obama is an Arab" (^ YouTube)
Is Orly Tatz before this judge?