I think it's fairly reasonable to.

That statement was made some time ago, and none of the crew, writers, or cast have come out to refute it or say otherwise in the last many years since James made that statement during a panel.

Additionally, in my experience it's been the opposite - Joss doing something without much thought but it catching fire when he didn't mean for it to or when he wasn't trying to make a statement or take up for some greater social cause. I've seen various interviews where Joss right out admits it, even including Willow's relationship with Tara.

Also, I'm not sure it's obvious what his exact motivation would be for lying to James during a private off the record conversation that he didn't know would be repeated down the line.