First let me say I work in medical research governance for a large NHS University Hospital, and am based in a University.
I think I can see part of the problem here: "enrolled in a March 2015 sports science experiment on the effects of caffeine on exercise.". Specifically the "sports science experiment".
As the participants were probably recruited directly from the student population I would assume that being a university the study would have been through an internal university approval process involving some kind of university Research Ethics Committee (REC) but probably no external scrutiny and possibly without input from a pharmacist or a medically qualified person.
Had the study been run under a medical school and had NHS involvement (which happens a lot) then it would have been a whole different thing.
This study would have needed approval by the Health Research Authority, an NHS REC, which would have been made up of medically qualified people. Also as the caffeine/orange juice mixture would be defined as a Investigational Medicinal Product (IMP), basically a drug, so the study would have also required approval from The Medicines and Healthcare products Regulatory Agency (MHRA) as well.
The IMP would have had to been made by a qualified pharmacist working in a pharmacy that had a licence to manufacture the IMP with very strict SOP's in place as to how the IMP is made, stored, distributed, used and destroyed if not used.
I just find it mindbogglingly unbelievable that this study would have been allowed to be conducted under the circumstances it seems to have been run!
PS To put on my pedants hat "...were mistakenly given as much caffeine as what's in 300 standard cups of coffee." seems like the author studied at the Ernest Wise School of English!
PPS The term IMP always makes me think of the great Terry Pratchett and the various Discword devices that have actual imp's inside them, like Twoflowers camera or Sam Vimes organiser. So every time I read a research protocol and read about what's going to be done to/with the IMP it always brings a smile to my face.