He doesn’t have an injury due to Obama’s eligibility, but due to his refusal to deploy. That does NOT create ‘standing’ to challenge Obama’s eligibility.
Since Obama is the presumed President, showing he is ineligible today would not change the legality of the orders given to Lakin, and thus Obama’s eligibility is not relevant to the case.
That has been pointed out many times over the last 4-5 months, but birthers don’t want it to be true so they keep ignoring it - just as they screamed a few months ago that the military judge would have no choice but to allow Lakin access to Obama’s birth certificate.