They're confused about this.
The main problem is the lack of clear examples of plants being handled in undignified ways. Such examples would have given the guidelines more normative heft. One of the few examples given is "terminator technology", modifying plants so that their offspring are sterile. Does this imply that seedless grapes or any of the other commonly used agricultural plants that do not reproduce sexually are an affront to the dignity of creation?So don't just go on heedlessly
eating grapes grown seedlessly!