Its actually stated: " As the Blue Flame upgrade is rarely utilized as a harassment tool, this change is added to allow Hellions with Blue Flame to 2-shot workers of all races. This might also help underused mech playstyles in all matchups and promote generally more active early and midgame from the Terran players."
Meaning they want to buff mech terran (hellions as a harassment tool). Which is still a turtle style. You can then use some hellions as a harrassment tool to kill more workers → its a buff for turtle or in other words: turtle style is getting promoted.
I played tons of matches vs turtle mech terrans that harassed with blue flame hellions. Hellions. Not hellbats.