Low totals are a fast track to bad fantasy games for most quarterbacks. Josh Allen is not most quarterbacks.
Looking at all players with 50 or more carries, only Mitchell Trubisky has averaged more Rushing Net Expected Points (NEP) per carry than Allen, who's at 0.55. Only Todd Gurley has more total Rushing NEP. Allen is rushing more efficiently than almost any quarterback and has the fourth-most carries (64) for a passer this year while missing four games.
With LeSean McCoy and Chris Ivory both questionable for the Buffalo Bills game against the Detroit Lions, the Bills may be forced to lean on Allen even more. Given his rushing floor, no total should scare fantasy players off. Not even the 39.5-point total of this game. Allen has also averaged 10.1 more points when the total is below 40. This doesn't necessarily mean he's better when there's less scoring, just that it doesn't matter for him.