You have to frame it in familiar terms for Mensa members:
What conclusions can you draw from the following sentence?
"I would posit that most normal, healthy, high-IQ folks never bother, and there's a selection bias at play."
a) All Mensa members are unhealthy.
b) There may exist some normal, healthy, high-IQ folks in Mensa.
c) All Mensa members have high IQ.
d) No Mensa member has high IQ.
What conclusions can you draw from the following sentence?
"I would posit that most normal, healthy, high-IQ folks never bother, and there's a selection bias at play."