The SCOTUS ruled that the owner was not in violation of discrimination based on refusing to make a cake to celebrate a homosexual marriage.
No matter how they or you parse it, this ends the ability to claim someone is discriminating against you based on their refusal to provide a cake to help you celebrate your cause.
Therefore it is not a narrowly based decision.
Under the laws in place in Colorado at the time. Those laws gave businesses some latitude to refuse to create specific messages they considered offensive. At the time gay marriage was also illegal in the state. Since then gay marriage is now legal and the anti-discrimination laws have changed.
No matter how they or you parse it, this ends the ability to claim someone is discriminating against you based on their refusal to provide a cake to help you celebrate your cause.
In this particular case, yes. There are other cases working their way through the system concerning businesses refusing to do work for gay marriages. This decision may or may not support upholding those.
Therefore it is not a narrowly based decision.
I guess our definition of "narrow" as applied in this situation differ.