“A Christian who has been baptized and who has received the sacraments of the Confession and the Eucharist, regardless of what have been his crimes and sins, as he dies reconciling with God and with the Church has the right to have a Holy Mass celebrated at his funeral,” the group said in a statement.
I agree with the SSPX here. If he reconciled with God and the Church, then he has a RIGHT to the funeral.
did the main Catholic church refuse to accept him for confession or what?
No one but God knows what was in his heart at the moment of his death, but after he died, his lawyer released a statement he had written on his deathbed which continued to deny his guilt and also denied the Holocaust (he claimed the ovens at Auschwitz were actually kitchens to feed the prisoners). So, IMHO (and speaking as a non-Catholic), the Pope was right to deny him a church funeral.