The Lord may have called them to do this thing and it is not for us to judge them. If the Lord did not call them for this task, He will take measures to correct their thinking.
Very good point. I'm not trying to judge (I don't think I am, but I'll pray about that), I just feel sorry for their families if any harm comes of this. I also fear that Christ may be marred in the minds of those who may see these ministers entering or exiting a porn convention. While they may not be sinning against their own bodies (sexual immorality is the only sin that is committed against one's self) they may cause another brother to stumble.
I make mistakes in judgement also. I would hope that someone would raise their concerns with me if they feel that I am misguided. I believe that is called accountability, not judging.
If God has indeed called them to this ministry, then they will know it and should not heed anyones concerns.