This is up to the people involved and depends on their individual personal relationships to God and Guru.
I disagree with the assertion that "homosexual sex between 2 consenting adults in a monogamous, committed relationship is wrong". Other Sikhs disagree with me; Indeed, this is not addressed in the SGGS because homosexual sex is not mentioned in SGGS.
Lust is more accurately understood as any sex between people who are not in a committed and/or married relationship, and also it is over-attachment to sex and sexual objectification of another.
If you study Siri Guru and read it cover to cover you will see the same message over and over: meditate on the Nam. Be compassionate. Battle the 5 temptations of lust, anger, greed, pride, and attachment. Serve Guru, serve sangat. In this way be liberated from the cycle of births and deaths. I do not see why 'married' homosexual Sikhs cannot live this way and be liberated. They are still living as householders. And I cannot imagine any of the 10 Gurus refusing darshan to someone because s/he is homosexual.
Guru ang sang - DK
