They didn't even have to absorb the tax. They could have just done what every other business does and passed the tax on to the customer. So your 40c magazine (the price they were selling at in Australia before they stopped charging for them) is now 45c: so what! It wouldn't dent sales, and the householder would still get change from a dollar for two magazines.
They were a successful publishing business and they threw it all away because of some stupid aversion to paying taxes to "evil government". In this case, believing their own propaganda (well, part of it; they didn't believe the "render unto Caesar" part) ultimately destroyed their underlying business and sowed the seeds of their current demise.