They don't share their system but do quote in the article that Ohio St has over 11 Million fans (about the same population of the entire state)... and the only place I can find that says tOSU has 11M fans is from Altimore's fan base rankings from 3-4 years ago... so that's a huge red flag to start off with.
"The list is reflective of the current enterprise value of each program, starting with a base revenue multiple of four for all institutions, and then adjusting the multiple for variables, including conference affiliation, estimated NIL spend, school subsidies, number of alumni and other factors that can catalyze future revenue growth and profitability."
GIGO. Garbage in = Garbage out
Especially inaccurate for private schools and especially low for BYU and the new Big12 members as they have yet to reflect the ramped up revenue numbers that will only be coming out in the next couple of years...