I question that the single rotor will cause undue flexing of the forks. Althought the pads grip the rotor on only one side, the braking force is applied between the contact patch of the tire and the pavement. As this force is centered between the forks, I fail to see how any undue forces are generated asymetrically. If flexing or twisting of the forks was the case, the bike would pull to the left when applying hard front brake. This does not happen, No matter how hard I apply my front brake during quickstops, the bike NEVER pulls to the left.
As there is adequate stopping power with only one front disc, I feel certain that the decision to use only one was dictated by economics.
Over the years there have been many scooters and cycles manufactured with only a single front disc. Until the machines got much heavier, there was not a need for dual discs, and to my knowledge, there was never a problem with fork flexing, even with fork tubes much skinnier than those on the Majesty.