The salient points appear to be: 1) that all solid waste needs to be processed to become useful compost; 2) most commercially available, composting toilets are not suitable for a short term, heavy load; 3) those suitable for a long term light load need to be maintained and sensibly sited.
The traditional Earth Closets (a hole in the ground with a seat box or straining bar over it) are possible but need to be situated very carefully as they are basically just a hole in the ground and holes fill....
As for the urban myth, read my post again - and then go and read anything about sewage works. The best tomatoes grow in untreated sewage, the seeds having been passed through the human digestive system unbroken (in the manner of sweetcorn and certain nuts) but would you want to eat them (I wouldn't, I don't like tomatoes)? The key phrase which was used several times is "after it has been properly handled" or "taken away to be processed".