Yes, libertarians would and do argue that anti-discrimination laws are unhelpful precisely because they involved coercing both actions and use of private property. Most libertarians I've talked to view the portions of the Civil Rights Act that coerce the actions of individuals or their use of private property to be a ill-guided and would rather people "vote with their wallets" (e.g. by boycotting racist businesses.) However, libertarians do generally agree with the 14th amendment that the government should treat people equally. So, a state targeting a particular race for citations or favoring a particular race for hiring would be a no-go with most libertarians.
Incidentally, the U.S. Constitution also bans what Oregon has done here (and what others in other states have also tried to do.) The U.S. Constitution quite clearly says that
"Congress shall make no law... infringing on the free exercise [of religion]."* While this initially limited only the actions of the federal government, the ratification of the 14th Amendment applied this restriction to the state and local governments, as well. As such, forcing someone to implicitly or explicitly condone a homosexual wedding in violation of their religious beliefs is explicitly unconstitutional. I expect that these laws will be struck down on that ground, probably by the Supreme Court.
One ironic point of people trying to use the Civil Rights Act here is that the it also contains this beauty, codified in 18 USC 242:
Whoever, under color of any law, statute, ordinance, regulation, or custom, willfully subjects any person in any State, Territory, Commonwealth, Possession, or District to the deprivation of any rights, privileges, or immunities secured or protected by the Constitution or laws of the United States, or to different punishments, pains, or penalties, on account of such person being an alien, or by reason of his color, or race, than are prescribed for the punishment of citizens, shall be fined under this title or imprisoned not more than one year, or both.
As such, the state officials who passed the laws fining the bakeries, florists, etc. could be fined and imprisoned under this law. Frankly, I think they should be in order to send a message that such violations of Constitutionally-protected civil rights will not be tolerated.
* In case anyone is wondering, no, I didn't change the meaning of the relevant clause at all in the abbreviation. The full text is
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof."