"constrained about" is correct and can be used in written English.
It means to be limited or restricted by something. Example: The company was constrained about expanding their business due to financial constraints.
And there is nothing constrained about Attenborough's manner of speech.
But I don't need to be constrained about the emotions that tragedies like this raise.
A local police commissioner should not feel constrained about testifying before the city council about such matters.
"We're not constrained about how we locate computers; we don't have to build them into the building".
But with the roles of caregiver and cheerleader thrust upon them, they may feel constrained about expressing their darker feelings.
"It cast such a large shadow that people here still feel constrained about speaking up," she said.
She demonstrated there that the attraction of the genre for a serious writer is its flexibility: what seems constraining about form and structure is actually liberating.
Given that the mobility of gene loci is usually constrained to about 0.5 μm in mammalian cells [ 31], it is likely that these gene loci are contacting the NL at a significant frequency.
On the basis of new rigorous methods of laboratory data analysis, a and b were constrained to be about 0.05, about five times larger than previously believed and c was constrained to be about 2.0.
One of the best movies I've seen recently is Nagisa Oshima's last film, "Gohatto" (1999), about the stern codes of samurai warriors and the violent passions that those codes constrained — and about the political order that they defended, reinforced, or threatened.
The resolution of conventional optical microscopy is constrained to about 200 and 500 nm in the lateral and axial plane, respectively, because diffraction sets a physical limit for the theoretically achievable resolution.
