Stevens draws too strong an analogy between Cadman and Stronach. Stronach had legitimate reasons for changing parties: she was to the left of the Conservatives; under the new leadership of Stephen Harper, the Conservatives moved a lot further to the right. She approached the Liberals about switching; it wasn't, as Stevens says, that Martin "wooed" Stronach. The cabinet post given to Stronach might have been slightly smelly, but nothing worse.
Offering a financial incentive to an MP is a whole nother kettle of fish. The Conservatives possibly did something illegal, and it's right that their actions are being investigated by the RCMP and the Ethics committee.
Morally, the Conservative actions are even more odious. To offer a million dollar insurance policy to a dying man is a particularly nasty form of bribery. Luckily for Mr. Cadman, it seems that he wasn't so desperate that he felt he had to take the deal. Had his financial and family circumstances been different, he might have been coerced into it.
Furthermore, the Conservatives were at that same time trying to muckrack over similar issues. The tape proves that Harper knew what was going on with Cadman - even as he acted all sanctimonious while he accused the Liberals of a much milder form of the same thing.