Cypress mulch is safe. Cypress does not have thujune in it like cedar does. It also does not have the resin issues that other conifers like pine do.
That said, if it was sold as garden mulch it probably has a lot of hitchhikers. Its also not as good as coco coir for a few reasons. Primarily those species whose nymphs dig in and the way it retains and releases moisture vs. coir. I do use it in mixed substrates where I also have leaf litter and aspen shavings mixed into coir.