again: i'm not a muslim. i don't have a moral problem with usury. i'm not going to support an anti-debt bill for the sake of it. if consenting adults want to sign an agreement, it's up to the courts to regulate it, and that goes equally well for everything else that muslims don't like: divorce, child support, mortgages, pay day loans and student loan debt, too.
so, if the government wants to step in and cancel a debt that was taken out by citizens to attend an institution that is public in scope, that is a question of democratic oversight. if there is support for this, it is up to the people to enact it.
but, for a government to cancel a debt held between a private citizen and a private institution, even if it is acting as an intermediary in the loan, would be overstepping it's bounds and interfering in a process that should be determined via the rules of contract law and regulated by the courts - an area of law that is far more flexible than classical liberals would have you believe.
my position is actually that the government didn't do it's due diligence in researching my background before it gave me the money, and the loan should be declared a gift for that reason. if a banking institution doesn't do it's due diligence, it has no right to expectation; that is, the courts have determined long ago that if the bankers give money to people they had no reasonable expectation would be able to repay the loan, then the debt can be declared null and void. consent requires competency. i could very well argue this in court, one day. for now, i just ignore the loan collectors.
but, the point is that the issue of private debt is not up for the government to regulate, but up to the courts to deal with. public debt is a different issue - that is a question of the public will.