Why this conservative is against (some) right-to-work laws

Conservatives typically support right-to-work laws. On most issues I could be considered a conservative, albeit with some libertarian tendencies, and I'm a strong advocate of the free market. It is precisely this free market belief that motivates my opposition to (some) right to work laws.

Wikipedia defines right to work laws as those

...which prohibit agreements between trade unions and employers making membership or payment of union dues or "fees" a condition of employment, either before or after hiring.

Now, I'm not really a strong fan of unions. However, I also believe in the employer's freedom to hire who they want. Here is an important distinction: if the government requires people to join a union to work certain jobs, or requires certain industries to hire only union workers, I am strongly opposed to that. If the employer requires union membership as a condition of employment, that should be fully within their rights. That is, as long as that requirement was made clear before hiring. While the common definition of "right-to-work" means the employer cannot choose to hire union-only, I would not be surprised if some variants are meant to repeal state government guidelines. Maybe somebody with more knowledge of these laws could help me out on this.

The common argument for "right-to-work" laws it that people should not be "forced" to join a union in order to get a job. However, if this is a requirement of the employee and NOT the government, no one is really being "forced" into anything. In the same way, just because being a Christian may be a requirement to work at a certain church, that doesn't mean I'm being "forced" into Christianity.

Another important note is that this swings both ways. A company should have the right to hire union only workers, and they should have the right to not hire union workers. Freedom works both ways.