In looking at the page, it looks to be pullout strength, the 50lb rating is for 1/2" board, 75lbs pullout strength for 5/8" board. The anchors should work fine, as originally thought by the Axiom pastor. \:\)

Description Pullout (ultimate average lbs.)
Gypsum Thickness

..................3/8" 1/2" 5/8"
Light Duty Plastic 25 30 40
Light Duty Zinc ...30 40 50
Medium Duty* ......40 50 75
Twist-N-Lock ......65 75 80
Heavy Duty ........70 85 150

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85