It was a collectively traumatic incident
A man, who the commenters do not know personally, collapsed and some people administered CPR and used a defibrillator. People watching could have turned off the TV or looked away and done something else at the point at which they wish the BBC had done so if they found it distressing. Sure, it might be actually triggering for some PP, but for the vast majority of onlookers, to say it was traumatic to have it on TV is to play fast and loose with the word trauma. They'll have seen worse on TV before. Mildly upsetting or shocking does not equate to traumatic. It probably was traumatic for his family, and for some of his team-mates.
I googled 'collective trauma' to check whether you had a point before posting in response to it and found lots of studies about war and natural disaster. Wikipedia says:
'Well known collective traumas include: The Holocaust, the Armenian genocide, Slavery in the United States, the Atomic bombings of Hiroshima and Nagasaki, the Trail of Tears, the Great Irish Famine, Attack on Pearl Harbor, the MS Estonia in Sweden, the September 11, 2001 attacks in the United States, the Halabja chemical attack and various others.'
Bit of a stretch to say that watching someone collapse on a football pitch is a collective trauma that must be processed on social media. And, if it must be 'processed', the vast majority of onlookers have people they can process it with IRL, or in private virtual spaces, rather than needing to have it trending on Twitter, Facebook etc. to facilitate their 'processing'. Ultimately, what drives the posting is the, 'Ooh, you'll never guess what happened just now- did you see?' impulse. Which is, ultimately, gossip, however you want to dress it up.