Seeds are not manufactured by plants overnight. It can take roughly 10 to 14 days or more, depending on strain, for seeds to form. Your buddy will almost certainly have at the very least tiny soft immature seeds that might not even appear to be seeds if your buddy harvests soon to hard shelled fully mature beans if your buddy waits long enough before harvesting.
Your buddy faces something of a conundrum in that once seeds begin to form energy otherwise used for other important function, THC and other cannabinoid production and terpene production for example, will be transferred to the creation of seeds so as the seeds are being made less energy will go for other far more important and desired functions.
Hormonal changes associated with seeding definitely affect all metabolic processes within plants including cannabinoid biosynthesis. An imbalance is created in the enzymatic systems controlling cannabinoid production. It is also suspected that capitate-stalked trichome production might cease when the calyx is fertilized.
Long story short --- your buddy's plants will eventually reach a point of diminishing returns, THC-wise, if he allows his plants to grow long enough. With THC/terpene production restricted if the plants are left to grow until the trichomes cloud and then begin to turn amber each day THC will be lost as it oxidizes and becomes CBN and it will not be replaced so the potency of your buddy's plants would begin to decrease at that point.
Your buddy will have to decide for himself if he would be better off harvesting early or wait and risk seeds and decreased amounts of THC/potency.
