I'd stop well short of labeling Minister Garneau an embarrassment. He is certainly qualified for his portfolio and is better equipped than any other MP, or indeed we critics, to weigh the pros and cons of such issues. As is generally the case, he is weighing factors we aren't privy to.
As government decides to enact many new regs, legislation etc; they just as frequently decline to enact others. I can only assume they balance a risk assessment, the cost to the public coffers, cost to the traveling public, cost in political capital, support within the House and that old chestnut: special interest groups/lobbyists.

The current CARs are in my opinion adequate to address most cases of pilot fatigue (particularly in 705 operations), and have steadily improved over the years I've been flying. I suspect the positions taken by the pilot unions and the airlines are rife with hyperbole, exaggeration and doomsday predictions on both sides. And it's extremely hard to quantify whether any changes in duty day regulations actually make a positive difference.

I half wonder if fatigue played much of a role in the SFO incident at all. It's a very easy claim to make as a pilot facing a career-altering investigation, and one very difficult to prove or dismiss - particularly in the absence of any CVR interpretation. Consider any new regulation introduced by the Minister would not have stopped the pilot's children from waking him up early on the morning of the flight in question.