Mohler is saying that many Christians will not reach out to homosexuals. He clearly affirms that homosexuality is sin, but also is affirming that it is not the unforgiveable sin.
It sounds as if he is recognizing that it is a difficult lifestyle to escape from for those who will listen to the message of Christ. I agree with that. I consider it a lot like alcoholism....there might be fits and starts before one gets it right.
The line in the sand, though, is that it always and forever must be acknowledged as sinful and destructive. It must never receive a positive representation.
The impression I get from his position is that he is willing to compromise on the message to assuage the feelings of the "audience."
Certainly we should expect that active homosexuals may present themselves into the audience of a Sunday service, but they should never knowingly be admitted into the congregation.
Admitting them into the congregation allows their cancer to infect the whole congregation and soon the church is turned into a feel good social club and before you know it the pastor is a practicing homosexual.