It wasn't stupid at all at a time when the BC and Alberta governments seemed intent on bringing in two tier health care by the back door. Martin was a terrible PM and not publicly supporting universal health care was a dumb dumb hill to kill the Liberal government over. Layton was throwing Martin a lifeline. Martin preferring to drown instead was completely his own business.
If nobody is against single payer health care then just say so and move on. Seriously.
It's a strawman. People shouldn't have to go through visible purity or loyalty tests and be judged on them. This isn't the red scare.