Putting this up for argument rather than for agreement. I have read it twice and I am still not certain what it supports.
The dose-response is real but shallow at the top. Across STEP 1 and STEP 4 the gap between 1.7mg and 2.4mg is a couple of percentage points of body weight on average, and the average is carrying a wide spread — plenty of people at 1.7mg sit above the 2.4mg mean. If a dose is working and tolerable, "working" is the relevant variable, not "maximal".
Where I think it is weakest: the comparator does most of the work in how this gets reported, and it is not the comparator most people think they are citing.
What I am trying to establish is how much of the between-person variation is pharmacokinetic and how much is just adherence measured badly. If the honest answer is that nobody knows, that is a useful answer and I would rather have it.
Note on sourcing:
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.