Teams that have had two or less losses almost always win the SB.
This is not even close to accurate. Since the merger (and excluding the strike-shortened '82 season):
2 loss teams (11/31, 35.5% SB win rate):
W 16NE 04NE 03NE 98DEN 91WSH 89SF 86NYG 78PIT 77DAL 75PIT 73MIA
L 10NE 09IND 06SD 05IND 01RAM 99JAX 98ATL 92SF 90SF 87SF 86CHI 84MIA 83WSH 77DEN 75MIN 75RAM 74RAI 73MIN 73RAM 70MIN
1 loss teams (3/7, 42.9% SB win rate):
W 85CHI 84SF 76RAI
L 15CAR 11GB 04PIT 98MIN
0 loss teams (1/2, 50% SB win rate):
W 72MIA
L 07NE