I knew it was talked about.
I actually found a calculator that estimates how much a log weighs.
Assuming the log Dutch used came from a tree similar to Walnut (don't recall the tree used in Predators, so going with Dutch), and that the log was 6 feet long, with a diameter of 30 inches, it would have weighted 1643 pounds.
1643/5= 328 pounds
If it were more like the density of oak, it's around 1933 pounds. 1933/5 = 386 pounds.
I'll buy a predator weighs somewhere in that ballpark. So, if we're close here, it's reasonable to me that the dead fall weight used in Preadator was enough to put down a Pred. To his testiment, the Pred still wasn't dead, and had enough left to set off his self destruct. Still a bada$$ if you ask me, taking 3/4 of a ton dropped on your head.
Site for estimating log weights
https://www.woodweb.com/cgi-bin/calculators/calc.pl?calculator=log_weight