Yes, they don't describe the details of how the bay leaves were prepared, i.e. did they just dry and powder some leaves and pop the powder in capsules, or were there other processes involved? It does sound like the first option, especially since they mention that they have yet to identify what substances in bay leaves are actually having the effects (implies that they are using whole leaves and not doing any kind of pharmacological processes on them) - but there isn't much to go on about the process they used.
A quick look around suggests that bay leaves aren't poisonous or toxic so there shouldn't be any harm in your friend consuming them if he wanted to. Main dangers are eating the leaves whole as they are tough and may cut or damage the mouth or esophagus, and also the bitter taste! And of course not confusing them with mountain laurel leaves, which are related and similar-looking but actually ARE toxic.
Of course if your friend has multiple health conditions and takes medication there's no knowing what the potential interactions might be, so it's worth being wary. And as you say, it is a small study (I am particularly concerned by the fact that the 2g group got some odd results compared to the other groups - suggests that the group size is too small to properly ascertain actual effects vs. random variation), and seems almost too good to be true - and you know what they say about that!
But my feeling is basically, provided he is cautious and sensible and aware that his health situation is more complex than that of the people in the study, there probably isn't much harm in trying. Bearing in mind that I'm not a doctor nor a biochemist and have no standing at all to make any sort of recommendation!