I think that was the majority opinion’s goal, they think the line between what is speech and what isn’t should be spelled out more minutely with more legal precedent rather than what we had before where all speech in relation to selling a service was regulated under anti-discrimination statutes.
People can do that now, but only for occupations that qualify as “speech”. Owners of “public businesses” (i.e. places that you can walk in to) still aren’t allowed to forbid entry to people arbitrarily.
I’m not sure about discrimination against customers based on ideology, but I’m pretty sure you can’t discriminate against customers based on protected class (sex, race, orientation, etc.) What this supreme court case does (IIUC) is that companies are now allowed to not provide services to protected classes if those services constitute speech. So if you are a restaurant owner, or a hotel, you still can’t refuse a gay couple, if you are a cake designer, you can’t refuse to make a cake, but you can refuse to do anything remotely gay-related to that cake, if you are a web designer, you can refuse to make something altogether because the government can’t restrict or compel speech (and graphic design is speech).