The fact that the club is now allowed to play their AFL listed players in the SANFL, does not make them any less the Magpies in the SANFL, To the extent that the club of Williams, Motley, Ebert, Quinn etc. is capable of becoming a reserves team and somehow retain its essence, sure. Yes, there is a team running out in the Sanfl wearing black and white and calling itself the Magpies. But surely a club's substantial, rather than superficial character is what makes a club?
I'm not in any position to tell Port/Power/magpies fans why they should or shouldn't support which team. However, objectively, this is the story:
A big change happened in 2014. While numerous changes have occurred to the club over 140+ years, the common thread from 1870-2013 was that the Magpies were a sovereign club, playing to win the flag, and not subservient to an AFL's teams developmental and tactical experiments. This year, that changed.
This year, the team exists to give the Power's young/unfit/crap players a run, and to try various things, teach Irishmen how to play, etc. From 1870-2013, it was 100% focused on winning the Sanfl premiership. Now it's about winning the AFL flag; the Sanfl is secondary where an inconsistancy arises. I.e. a reserves team.
Winning flags (in the comp it played in) was always the one and only goal of the Magpies I knew.
Surely, after changing to such an essential degree, this team can't claim to be the Magpies anymore. As Wedgie said, you can call your son Gary Ablett Jnr. Doesn't mean you're Gary Ablett. (Thanks to Wedgie for the analogy! :))