[Nateman]

...T-Rex did not need arms to choke the prey.

Imagine a tiger with stubby little arms. Not much of a tiger now is it? Those big T-Rex jaws were for busting open big bones.

[entropy12]

Front paws of the tiger is always his first strike at the pray. It is never the bite, first. So tiger needs strong front legs.

T-Rex on the other hand had those enormously big hind legs. My guess is he could run on 2 hind legs something like a kangaroo, and when he caught up with the pray, one bite of that long jaw with 6” long sabre teeth would instantly kill the pray.

A scavenger has no need for such long and strong hind legs. A hyena is the premier scavenger in Africa and looks more like a dog than T-Rex.

[AnotherUnixGeek]

Imagine a tiger with stubby little arms. Not much of a tiger now is it? Those big T-Rex jaws were for busting open big bones.

There's no evidence that forelimbs are needed to be an efficient predator. Snakes bring down prey just fine without them, and predators from wolves to weasels bring down their prey with their teeth and jaws. Cats with their retractable claws do make full use of their forelimbs in subduing prey, but it's hardly a requirement for a predator.

I'd guess T-Rex was (like most carnivores) both a predator and a scavenger, depending on what was available. No carnivore is going to choose to try to subdue living prey when a dead carcass is available.