Olly, overwhelmingly internet sites make the connection of the inverted pentagram with black magic. I have not found a single site referencing your interpretation.
Looked up Manly P. Hall and found this:
"Manly P. Hall, an occultist, points out that the, " . . . pentagram is used extensively in black magic.'
Read 'Secret Teachings of the Ages' yonks ago, don't specifically remember much.
Finally found what you were stating here, but it is only a blog-site, unable to find it in relation to Hall though.
"Inverted Pentagram * The pentagram may be inverted with one point down. The implication is of spirit subservient to matter, of man subservient to his carnal desires. * The inverted pentagram has come to be seen by many pagans as representing the dark side and it is abhorred as an evil symbol. Fundamental Christians, indeed, see any form of pentagram as such. * However, these are recent developments and the inverted pentagram is the symbol of Gardnerian second degree initiation, representing the need of the witch to learn to face the darkness within so that it may not later rise up to take control."
During the mid-seventies there were shocking revelations in Australia regarding the huge number of Freemasons in senior government bureaucratic positions in Australia. I think associated corruption was involved, but can't be sure as I was at school then.
The Freemasons do not however include the 'discs' (wreath in the Vic police emblem), however Satanists do.