Sure, but would the bookies set the opening price on who they might rationally think will win, or on which side they think will attract the most money. The latter I think.
No way.
They will always set a market based on how they see the result playing out.
If they get it badly wrong, they stand to lose a fortune. They want to set the odds and the line such that the spread of money from punters is fairly evenly split and they make money on their margin. If they weigh the odds too heavily in one direction, all the money piles on that way and their risk increases dramatically (i.e. they can either win big or lose big). They then have to lay some of that risk off with other bookmakers which costs them a margin.
Clearly the results over the first two weeks of the Rugby Championship will have an impact on the market because it provides more information how the two teams are travelling.
Bookmakers try not go gamble. They aim to make money on the margin (i.e. the even money bet pays out $1.90 for every $1 bet).