I know a couple of guys it happened to. Travelled while on ED Visa. Questioned about their progress kn the Thai Language course ie none. Refused entry on the ED and it was cancelled. Riles and the whims of whoever is in charge can change overnight. When "Big Joke" became head of immigration the Volunteer Visa disappeared almost overnight. Even legit places now cannot get these visas to legit volunteers.
The question being asked though is regarding re-entry or extension once your soft power course or treatment is over. What happens if the Immigration Officer wants to see proof you are still eligible ie ongoing enrollment or treatment?
It is crazy when you think about it. As I have said this visa was the brainchild of the Ministry of Foreign Affairs and not Immigration. In the UK it would be like the Foreign Office opening the doors and handing out visas without consulting the Home Office :-)
Are you sure that was the Minister for Immigration? If it was with the Canadian bloke "Retired working for you" it was NOT immigration - it was MFA (Ministry of Foreign Affairs)