You don't need a full exploit to use everything, it's simple enough to do with just the ELF Loader to access all 3 cores, with kernel giving some extra permissions. MN1 even has a fully working OS Loader with source ¯\_(ツ)_/¯I was the beta tester from Project Trinux, if I not bad remember it was decided to stop development in the altered vWii mode with 3-core support because of a lot of limitations that were hard to supercede like RAM or full GPU support or max clock speed ,etc...
@TeamScriptKiddies know a lot about this since he gave to me some loaders to initialize with Trinux .
The development will start again when Wii U side is fully hacked, since it will be a lot easier to work with it (Applications runs in the GX2 at 550MHz, Full RAM support, Max CPU cache and Clock Speed ,etc...)
https://github.com/wiiudev/libwiiu/blob/master/examples/osldr/src/loader.c