Yes I can answer, and in the interests of helping I'm happy to talk the hard stuff.
My Chris went into a starvation mode by refusing the peg and having increasing difficulty in swallowing. He was dehydrated as well.
He did then say he was ready for the peg. But he had passed a point of no return both physically and mentally as he also had FTD.
I was able to keep him hydrated, but he never managed to put weight on, he kept losing weight albeit a little slower than before the peg. He would be nauseous after slow small feeds and refused real blended food, preferring to simply refuse a feed because I think that gave him a higher sense of having some control by saying no. Please do understand anyone reading this that he had FTD and I knew him very well, I'm not suggesting this about other PALS, but this is what was happening here.
They become less and less hungry as the digestive process slows down and they will have less and less energy as the calorie input is lowering. If he is also not using bipap then the energy will decline even further.
What I do know of many other PALS who did not wish intervention is that good palliative care can give a very peaceful time as they decline. It is still a very individual thing as to how fast or slow this will be. For my Chris the aspiration pneumonia really did tip things, mainly because on top of the toll it too, he developed many fungal infections from the fevers and antibiotics and he declined fairly rapidly. He was the most peaceful in his last week of life as we could give him effective palliative care at home.
If your PALS does not want anything like peg/bipap I would highly encourage you to check out your hospice services and have them discuss with him what his wishes are so you can plan with him.