You picked up on one negative unrelated(Not about safety) statement and ignore all the parts about how it is generally safe.
You are absolutely correct.
The problem is about the efficacy of prophylaxis.
The mosquitos are adapting to CQ after 75 years and no longer used.
When I was in RVN they added one small white pill daily from (IIRC) one large pink pill a week for this problem.
A side note:
Distant kin that works in a hospital tested positive for Wu-flu, a few days into quarantine developed breathing problems. On admittance to the hospital was given CQ and put on oxygen. Released in a couple of days, more quarantine and just this week returned to work.