They would need to have been ingesting or breathing the glyphosate pretty recent to their blood draw. It doesn't absorb easily into skin, and it passes through you quickly. And if you do get a concentrated dose, you get nausea, vomiting, respiratory issues (if inhaled). It's a weird thing to be the culprit, since it's hard to get, and doesn't cause many issues. And it's weird to mention at all, since he says only "a few people" had elevated levels of it.

"Melissa Nicholson said her 59-year-old mother, who has suffered for four years with a neurological disorder, received test results indicating she had levels of glyphosate in her body that were 47 times higher than the acceptable level."

This is bizarre. Either she lives right next to a farm that's spraying it, and she's getting it blown into an open window in her house where she's breathing it, and then immediately went for a blood test... or she's somehow ingesting it in/around her house (like from a bottle of Roundup that keeps getting splashed on something she's ingesting).