Judge Walker did not seek out the federal challenge to the California voter initiative banning same-sex marriage, it was assigned to him. The main concern at the time was not that Walker might be biased against Prop 8, but that he might be too conservative.
The Chronicle reports via SFGate.com: "There is nothing about Walker as a judge to indicate that his sexual orientation, other than being an interesting factor, will in any way bias his view," said Kate Kendell, head of the National Center for Lesbian Rights, which is supporting the lawsuit to overturn Prop. 8.
As evidence, she cites the judge's conservative - albeit libertarian - reputation, and says, "There wasn't anyone who thought (overturning Prop. 8) was a cakewalk given his sexual orientation."