Honestly, it sounds like they both want it all. You can't take one pot, that's causing tension because it's a bit too small (i.e. her not working) and divide it into two bigger pots.
Sometimes it's good to try and write down the blunt realities, not the moral discussion:
If the house is a reasonable size and of reasonable asset value how will she fund the bills - heating, electric, council tax, running a car if it's not town centre, maintenance etc. A small part time salary isn't going to cover that and food, or is it? She's not going to get benefits if she's an empty nester. The house is unlikely to be something lovely for the DC to return too if she's living in poverty in it.
Selling/ valuing the house and valuing the pension pot accrued during the marriage (no doubt pretty much all of it to date) would be a good first step. That along with any savings gives a rough total marital assets pot. Roughly that then divides. I'd say (based on life, not professional experience) she's more likely to get over 50% of the pot value as she's been homemaker and has less future potential to earn at the same level as your DB. So say the pot is to be split 60/ 40 in her favour. Can your DB keep his pension and just start afresh? Or, is he better off letting her have a slice of it and getting a cash settlement from the house that becomes a deposit on another house.
It may be that he feels negotiating a small regular payment to her for X years and is a better arrangement than having her named on the pension.
Divorce starts off through mediation so having lots of options to table, being flexible but also realistic are important.