Although Matthew had added the spider silk glands onto his wrists, it doesn't mean that the silk will be able to come out of his wrists if there's no hole where the silk could come out from. So Matthew added 2 micro holes on each of his wrists to enable the spider's silk to come out. And it didn't cost him any bionutrients since he could just ask the system to modify his body slightly just like when he changed the size of his wolf head or changed his skeleton structure from a quadruped to a biped.
The spider's silk glands were a nice addition, but his body modification has just started and it's still far from being done.
