He mentions getting advice on this forum several years ago and he just joined today :h
I did go to the site - Omni Lynx - and it sounds legit but it also states:
The OmniLynxâ„¢ Program offers access to an unlimited data plan that is not otherwise accessible by non-government users. Due to the potential for increased burden on network infrastructure during peak hours of utilization, the service provider reserves the full right to reduce data transfer speeds (commonly referred to as "throttling") as necessary.
So it is unlimited but subject to throttling.