Prolly doesn't get some of the finer points of parliamentary
democracy, like the role of the whip.
In a parliament, voting against your party (except in rare, well-defined circumstances usually called 'votes of conscience' by the government before the vote is actually held) is pretty much the same thing as quitting the party. In a parliament, this is a big deal, as theoretically any time the governing party loses a vote they my no longer form the government. In practice, the votes that cause the automatic fall of the government are restricted to what are called confidence motions; any money bill is a confidence motion, and other high profile things like declarations of war, plus anything the government says is a confidence motion.
The whip's job is to make sure the members are well aware of which motions absolutely require toeing the party line, and which ones allow more flexibility. While the ID card bill may not have been a vote of confidence (you'd know more about that, Peter), probably the government thought it was desirable to have all the members vote in favour, and instructed the whip to let their party's MPs know that voting against the government on this one was Not An Option (as is usually the case in parliamentary systems).
Voting against your party means not getting the support of your party when you need it, like during reelections, or when budget decisions that affect your riding are being made, etc etc. He may very well dislike this bill on principle, but think that it'll be better for his riding and his constituents in the long run if he goes with the party on this one.
This is basically similar to a Republican congressman voting for a bill he doesn't like since it's apparently a done deal anyway and he can use his vote to horse trade for considerations for his district at more important times.
