Son having issues

My son was called in to be interviewed by a social worker about an anonymous complaint. Given the details of the complaint, it could only have been his ex or someone she put up to it, that made the report. (she has made reports before, that went nowhere). He supposedly is drinking alcohol around the children, constantly and that he doesn't feed the 3 children properly. He is being made out to be an alcoholic, he is not. He works full time and takes good care of the 3 kids. Also it was reported that she didn't like the character of the people he was taking the kid's around. The children were interviewed a few weeks ago. When my son found that out, being proactive, he called and was connected with the social worker. When he said his name she seemed to panic and said she was too busy to talk and that she would call him back, which she did but weeks later.
My son pays child support, usually early because the ex always asks for it early. He has shared custody and has the children every second week.
She recently remarried and has a child with the new guy. The new child is getting all the stuff and all the attention now. The kids tell their father they are afraid of the new stepdad. They text their father often when they are with their mother asking to come back to his house because they don't like it there. I think she is trying to get full custody so she can get more child support. I think the new man is sick of her staying home and wants her to go back to work and this may be the way to get more money to appease him.
It doesn't seem a serious situation but some of the things the social worker told my son don't make sense. The social worker said my son may not hear anything more for a few weeks because they have real emergencies to attend to. She said her supervisor would decide whether to drop it or put a safety order in place.

1, The social worker said it's illegal to consume alcohol in front of children, in Alberta. (When he asked for the law, she said, look it up, if it is illegal, Google doesn't know.)

2, He shouldn't have his 16 year old son babysitting the the 11 year and 8 year old kids. When he asked who could, she described a teenager similar to the son.

3, He shouldn't take the younger children around his men friends because he didn't know if they were pedophiles. (really).

4, My son told the social worker that if he took the kid's to a neighborhood block party and didn't have a beer, The ex would still accuse him. The social worker said that he should video chat with the ex to prove he was not drinking.

5, My son and the ex should have mutual friends. I laughed when he told me that one.

6. The 16 year old boy knew of his father's appointment before my son did, said mom told him. The social worker must have told her, how else would the ex know?

7, The social worker told my son that all of the children told her they were excited to have their weeks with him but sometimes he gets angry. My son explained that when he disciplines by taking away tablet, phone or sending to room, the children say they will tell their mom and say he is being rude and mean.

The 16 year old told my son that he wasn't asked any questions about life at the ex's house.

Should he have a greater concern on what is going on?