The inverted cross even though originally a Catholic symbol representing St. Peter who was crucified upside down, has an Anti-Christian meaning. Inverting the cross would mean opposition to Christianity.
Wicca which is strongly faith-based compared to Satanism, would mean they are opposites. Did the founder come up with the inverted pentagram to show strong opposition to the religion of Wicca?

Page 136, The Satanic Bible.

Also: http://www.churchofsatan.com/Pages/BaphometSigil.html

Its time for you to do your homework, and stop asking questions that you can answer for yourself by simply reading The Satanic Bible and the contents of Church of Satan website.