I would not be surprised if there is a church or church-related org in the community that would gladly help IF they are reasonably believe that would solve a problem (rather than set up a repeat of the same or worse problem). This friend sounds like at best a clean-up would just restart the process of the house being trashed.
Then, too, c_d_l probably shares DU-folks' antipathy toward theologically conservative Christians. Many churches and church-related orgs that would help in that way are theologically conservative, so c_d_l would likely eschew enlisting such help.
On a more personal note, I had a family member that was a hoarder but for much less of a time and the home was basically sound and the individuals personal hygiene was acceptable. While I had help from other family members it fell to me to be the lead clean-up detail. To protect the privacy of this family member we did our absolute best to do the clean-up in as a discrete manor as possible. This is one of the reason why I find this thread so interesting. Contact the media???? Right.
I was of course working full time and had other family obligations but still I dedicated at least 1 full day every weekend and several after work hours at least twice a week. It took me 5 months to get everything picked up and another 6 weeks to fix everything (interior) that was broken or needed repairs. Trash pick-up was twice/week and for about 5 months every trash night I put 20 or more bags of trash out to the curb and then filled my pick up truck with more to put out to the curb with my trash. At the very end of the clean-up when all that was left was broken furniture and non-organic stuff I rented a dumpster. I also made three trips to the recycling center with a full size van filled completely with unread magazines. It took over two hours to unload the van each time! The whole experience was a complete nightmare.
So given my experiences I doubt that there would be any volunteer group that would step in and clean the place up. The OP said the friend started to decline 15 years ago so that probably means leaky roof, broken windows, plumbing issues, deficient structural issues, vermin infestation, in short a dangerous environment. There are professional outfits that will do the cleaning but they are not free by any means. And then you still have a structure that is at least 15 years past due with routine maintenance.
So I have this mental picture of the situation and it's just not taking the trash out, washing a load of clothes and restocking the fridge. If the floors in the bathroom and kitchen are not rotted through I'm sure they are at least on the way. Broken pipes/mold, broken electrical fixtures, carpets ruined, bedding ruined, holes in the roof, heaters/hot water gone, just on and on. It's a tear down.