Annabella, you may well be right, but also you may be wrong too. Many years ago, I once called the RSPCA on an owner with a cat which looked half dead, it was so thin, it's bones could be seen, it's eyes were bulbous and sad and if offered food it would gulp it down. I thought the cat to be half starved and uncared for along with many of my neighbours, all complained, but none did anything, so I did, I phoned the RSPCA. It turned out the cat was well cared for, had liver disease and had a vet history as long as my arm, they were holding on to having it pts because they didn't want to let it go, and as thin as it was, it was still eating and having a life, so quite the opposite to what we all had thought.
The owners who were new to the neighbourhood, made a point of talking to us all probably wondering who had phoned the RSPCA

But very nicely explaining that the cat was cared for. I felt a plank but I guess I still did the right thing.
Now, I always ask questions if I am suspicious from the person themselves, not someone who thinks they know and I try not to listen to tittle tattle. So by all means call the RSPCA, if you are really concerned, but you may well find that both dogs could just be old, or have health problems unrelated to care, the Husky may only be walked by the man himself because of it's condition, it may not walk too good, so may not have needed the dog walkers exercise. What I'm saying is it may not be neglect, a lot of our dogs when old or ill do go down hill fast and sometimes do not look that great.
If the man is taking the husky to the vets to be pts, the vet would soon know if it were neglected or if it has a history with him/her, not many people will take a neglected animal to a vet, which makes me wonder (if that is true) perhaps it isn't neglect just bad health.
By all means call the RSPCA as it is the right thing to do if you suspect cruelty but only do so if you feel the dogs are neglected from what you have seen and if you feel what
you have heard from the man does not add up, not from someone elses opinion on it. Be ready for the fact that it may well not be. :-) But if it is you've done the right thing.