From the article referenced above, in short: increased partial pressure of CO2
"I’m inclined to view the method Drew proposes as an easy way to decrease the risk of a stalled ferment when using the Dupont strain."
My 6 or 7 saisons using this particular strain 3724, never truly stalled and I never used heat.....my room temps (mostly low to mid 70's) with the foil over the fermenter opening led to steady if not mercurial fermentations, and some good beer.
Nah, it doesn't have to be sanitized, just my process. Shrugs.