I have great respect for a manufacturer's instructions; however, this makes no sense. A 60 tooth thin kerf carbide saw blade on a table saw will best a manual cut for most of us, both for accuracy and neatness. That blade will also go through thin metal pieces with no ill effect. Personally, I would cut a piece on the table saw and see if the world ends. If not, thats how I would continue.
What brand is this that specifies manual cuts? Can you imagine paying a pro to do that?