My understanding is that the 'G' aircraft are maintained by LAME and if applicable by the owner / builder of the 'G' aircraft so long as the owner did build the aircraft and has the appropriate maintenance qualification. An example would be a kit aircraft that is bought after being built by another would need to be maintained by a LAME or another authorised person (RAA to advise such in the near future and won't be any of the current L1, 2 or 4's; unless they do further training and qualification / experience.) Sounds safe and fair to me.