Specifically, these arguments make the false dilemma fallacy - the error of portraying one choice as necessarily excluding another, even though there is no necessary connection; and the false cause fallacy - asserting there is a causal link between the funding of the JSFs and other funding.
Even if one doesn’t like a particular political party, organisation or person, every issue should be treated on its own merits and in good faith. To do otherwise is to engage in dogmatic unthinking. Politically, announcing the $12 billion spending adjacent to discussion of spending cuts in other areas might not have been very savvy. However, a disinterested analysis recognises that one has nothing to do with the other, anymore than any other government expenditure.
The total 2013 budget for Australia is almost $400 billion. As this interactive shows, social security and welfare is $138 billion, education is nearly $30 billion, and recreation and culture is $3.7 billion. These figures are for a single year.
My understanding is the $12 billion had been accounted for in the defense spending cycle. Unless you are a complete pacifist who believes Australia should disband its military (in which case I say good day to you sir/ma’am, could you please leave my website and go back to playing with your imaginary rainbow unicorn), you will recognise the need for this spending. You might disagree with this specific program, on its own merits, but not based on some supposed link to another completely unrelated program.
Unless you can establish that Australia could spend, say, $3 billion less on alternative fighters that have similar capabilities; and that this $3 billion could go to another area of government expenditure, you are clearly interested in winning a political fight, rather than discussing a real issue.