I generally agree, but I think NRDC’s take is valid:

While bamboo is less environmentally friendly than recycled material and can be problematic if a bamboo plantation was established by clearing a natural forest, bamboo is a fast-growing plant with a much smaller land use and carbon footprint than Northern Bleached Softwood Kraft (NBSK) fiber, the form of wood pulp commonly used in tissue.

Essentially recycled > bamboo > everything else, which is why most bamboo brands got a B/B+.

What I think will be interesting is if we reach the point where the recycled paper market demand outstrips supply - I’m not sure if such a thing exists, but if there are any products out there that can work with recycled paper but not bamboo, then we may want to see more bamboo tissues to allow for recycled (other)