Hi J.,
My 19 month old daughter just barely started walking about two weeks ago. My advice, don't worry about it. I stressed and stressed and there was nothing wrong with her. She just didnt' want to fall. So now she walks, very slowly and carefully, and hardly ever falls and loves it! So, I'd tell the mom not to worry about it too much. Or have her call Early Intervention (through family enrichment in davis county). I had my daughter assessed and they were really great. They even come to your house. And typically, they can give you some ideas, or even hook you up with a physical therapist at a very reduced cost.
Okay, so for some ideas, what worked for my daughter is to not hold both hands, but just one. That forces them to hold up more of their own weight and not just HANG on you. The only thing you need to worry about is when they fall. Don't hold on to their arm if they fall down, just let him go. IF you hold on and he twists, you can fracture his arm. Just an FYI. So, try holding just one hand and see how he does. The other thing that worked really well was putting chairs, ottomans etc. just out of reach. My daughter would be cruising around and I'd put a toy on the ottoman that she just couldn't quite reach from the couch. So, she would take the leap and walk a little step to the ottoman to get the toy.
From what I've heard from pediatricians and physical therapists, walkers are not good for kids who don't walk on time. Just like you're saying, they will rely on the supports and not develop the muscles they need to walk. So, I would just not even use the walker at all.
Ultimately, the thing that worked best was just giving her lots of encouragement and praise when she finally did take the risk and let go of my hand, or even when she walked holding on to me. And really, kids will do things in their own time. Its great to work with them, but don't stress out about it. And if the mom is worried, get him assessed. It can't hurt and usually provides a lot of peace of mind for mom :-) It did for me!
Good luck!
J.