Looks like the medium post was updated to more accurately reflect what happened. A $100M Liquidity Mining Program was never launched. Only Atrix’s proposal was voted on and approved.
I just read the (updated) article. So, from what I understand, developers (and contributors) who help support the Serum network allocated this $100m in SRM towards the liquidity mining program. The DAO voting for Atrix was the starting point. The DAO will continue to choose where this money goes, with upcoming votes for Raydium and Mercurial.
And additionally, the total amount of SRM rewards to be allocated across all phases is ultimately subject to voting