Because a religious person/group has as much a right to live in accordance with their views as LGBTQ+ has to foster care.
The Court ruling did in no way impact the ability of LGBTQ+ outside of their dealings with SPECIFICALLY Catholic organizations. At that point the case crossed the line from disenfranchisement of LGBTQ+ folks to disenfranchisement of Catholics specifically.
You really think a 9-0 ruling would have been the result when folks like Justice Roberts, notably pro-LGBTQ+ as evinced by decisions like Obergefell v. Hodges, voted in favor of us Catholics?