While I hope its because he truly believes that woman should have the right to a medically supported home birth, I am a bit cynical... some politicians use controversial decisions by the party in power as a platform to get up there and go "see, you should have voted US in, we'd NEVER have done this..."
Political point scoring...wouldn't put it past any of them. But if a politician supporting home birth helps to make it 'legitimate' then TBH I am not really bothered by what their motives are KWIM? We still get the desired result.