This fellow was later restored it seems but until then he was in danger of losing his salvation for as Paul added in chapter 6:9-11 such actions (works) would bar one from inheriting God's kingdom.
The guy was not in danger of losing his salvation...He was in danger of losing his life so that he would/could be saved...
1Co 5:5 To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.
And no, Paul did not say such actions would bar one from inheriting God's Kingdom...
1Co 6:11 And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.
What Paul said as you can see is that prior to being washed, sanctified and justified, one would be in danger of not inheriting the kingdom...
And praise God for that...
Then a man in a sexual relationship with his step mother COULD inherit God's kingdom?
“What Paul said as you can see is that prior to being washed, sanctified and justified, one would be in danger of not inheriting the kingdom...”
Those unwashed, unsanctified, unjustified were not in line to inherit the kingdom and if Christians engaged in such things they would not inherit the kingdom either for they would be what Peter called “dogs returning to their own vomit and sows rolling in the mire”. (2 Peter 2:22)
Yes, some Christians had formally engaged in those practices but they stopped and had the vomit and mire washed from them.