The mother of a Syrian refugee detained over the Parsons Green bombing suffered a heart attack after hearing of her son's arrest, his employer said.
Aladdins Fried Chicken, in Hounslow, demanded a "fully unreserved apology" from the Metropolitan Police, accusing the force of labelling Yahyah Farroukh "a terrorist to the world".
The 21-year-old was released without charge on Thursday and his mother is said to remain in a critical condition in a hospital in Egypt after collapsing from shock.
Aladdins boss Suleman Sarwar said the takeaway had received "abuse, threats, anger, and hatred" after Mr Farroukh was swooped on by undercover detectives after finishing his shift last Saturday night.
He said: "The investigation brought Yahyah, his friends, family, place of employment and the wider Muslim community under scrutiny and indignity.
"Once again, the community has received backlash and animosity from the public."
Police continue to question four people, including a 17-year-old boy, in connection with the rush-hour bombing, while a 48-year-old man arrested in Newport on Wednesday was released without charge, Scotland Yard said.
The teenager was detained after officers raided what neighbours described as a "halfway house" in Thornton Heath, south London, at around 12.05am on Thursday.
The investigation into the attack, which injured 30 people, has also seen two men aged 25 and 30 detained in Newport, south Wales, and an 18-year-old man detained at the Port of Dover.
Warrants for the further detention of the 25-year-old and 30-year-old men were granted until Tuesday, police said.
Searches at an address in Surrey, one in Thornton Heath and two in Newport are continuing.
The bomb had a "large quantity of explosive" and was "packed with shrapnel " the Metropolitan Police Commissioner said.
Speaking to LBC Radio, Cressida Dick added: "Thank goodness nobody was killed at Parsons Green. It must have been absolutely horrific for the people in the train.
"As you know, many people suffered injuries.
"That was a very, very dangerous bomb. It partially detonated. It had a large quantity of explosive and it was packed with shrapnel.
"It could have been so much worse."
Ms Dick also paid tribute to the "wonderful response" of the emergency services attending the incident.