Republicans would still privately laugh at Kingsmill jokes, a family member of one of the victims has claimed.
Colin Worton said that made him angry, and urged Sinn Fein to do more to accept his pain.
His brother Kenneth was one of 10 people shot dead by the IRA during the sectarian attack in January 1976.
He said: "Words are only words, actions are what we want to see. We want to see everybody condemning it, and rightly so, and for it to be heartfelt and mean it.
"As far as I am concerned, this is only from the teeth out.
"Behind closed doors, I firmly believe there are a lot of Sinn Fein and their supporters who would still laugh at this joke."
West Tyrone MP Barry McElduff has apologised and resigned after posting a video on the anniversary of the shootings.
He said he had not meant it as a reference to the sectarian murders.
Shortly before his death, Mr Worton became a foreman at the Glenanne textile factory where he worked.
He had a wife and two young girls who were waiting for him to come home on the night of the attack, a recent inquest into Kingsmill has been told.
Colin Worton said he was sickened, disgusted and angry at Mr McElduff’s reaction. It was the "straw that broke the camel’s back", he added.
He said: "Until they accept my hurt, and whatever loyalists have done the same, their hurt where they have killed nationalists, all this has to stop. We have to move on, but we have to move on as equals, not to be remembering and even glorifying people who were in terrorist organisations."
He said glorification of terrorism, loyalist or republican, was wrong.