You could outwalk it if does not run, because this here was about walking speed.
---
As for T. rex's next steps, the study authors want to incorporate their flexible tail into models of a running T. rex, van Bijlert said. Maximum running speed for a T. rex is thought to be in the range of 10 to 25 mph (16 to 40 km/h), according to Hutchinson. Biomechanics researchers have long proposed that T. rex's maximum running speed would be limited by the strength of its bones, because the animal was so heavy. However, a flexible tail could change that by acting as a shock damper during running, "allowing it to run faster without breaking its bones," van Bijlert said.
Maybe you could outrun a fully-grown T. rex. But what about a juvenile?
This is a great zoom talk by Dr. Thomas Holtz about the role played by sub-adult tyrannosaurids: https://www.youtube.com/watch?v=XwxaEsLcU_w
Holtz looks at the hypothesis that juveniles and sub-adults filled the niches that medium-size predators occupied in ecosystems with no tyrannosaurids. If so they'd have needed to have been fast enough to catch smaller prey.
The most surprising part of the article, for me, is the population estimate of T. Rex to be in the billions.
Clickbait title. It's about walking speed which does not tell us about the running speed.
The article itself cites researchers saying: "the study authors want to incorporate their flexible tail into models of a running T. rex, van Bijlert said. Maximum running speed for a T. rex is thought to be in the range of 10 to 25 mph (16 to 40 km/h), according to Hutchinson."