Omar Salem said Laura Kuenssberg was doing her job "without fear or favour", after a Twitter storm in which she was condemned for potentially opening him up to abuse online over the incident.
After Mr Salem took the Prime Minister to task during a visit to a children's ward at Whipps Cross University Hospital, where his seven-day-old daughter is being treated, Kuenssberg told her followers he was a Labour activist, before linking to one of his posts about the incident.
It prompted fury from many social media users, with some suggesting it could "direct harassment" at Mr Salem, and causing #SackLauraKuenssberg to begin trending online.
On Thursday Mr Salem tweeted: "@bbclaurak is doing her job without fear or favour, which is a vital part of democracy. I don't think 'Labour activist cares about NHS' is a huge scoop though..."
The BBC had earlier said any suggestion Kuenssberg had maliciously shared Mr Salem's tweet was "absurd".
In a statement the BBC said: "Laura is a journalist who uses social media as part of her job.
"Like many others, Laura quote-tweeted a thread by Omar Salem, who had written himself about his encounter with the PM on social media and describes himself as a Labour activist.
"Any suggestions there was malicious intent behind her tweets are absurd."
The tweet of Mr Salem's which Kuenssberg shared read: "Boris Johnson dropped into @WhippsCrossHosp for a press opportunity - so I gave him a piece of my mind about how he is running the NHS based on the experience with my 7 day old daughter, who was neglected for hours last night."
During the visit, Mr Salem told Mr Johnson: "There are not enough people on this ward, there are not enough doctors, there's not enough nurses, it's not well organised enough.
"The NHS has been destroyed... and now you come here for a press opportunity."
Mr Johnson, who was wearing a 'Hello my name is' badge, an innovation pioneered by Yorkshire doctor Kate Granger, replied: "There's no press here," but Mr Salem gestured to cameras filming the confrontation, and said: "What do you mean there's no press here, who are these people?"