I don't think it can be justified really
People talk of Labour ruining the country, and that makes me think well, increasing poverty and attacking the disabled isn't seen as "ruining the country" then so, its all OK
Benefits fraud is a drop in the ocean compared to bankers, huge companies getting away with minimum tax etc but as ever, fraud is acceptable if its monied and wears a suit...(it reminds me of the tugging the forelock attitude that oh, those with money have always done whatever it takes to hold onto it so, its acceptable to the working man as just what they do) so there's a preference to look at the man across the road and be more scornful if he's caught out, or indeed even if not and its just someone on benefits they're looked down upon
There's a real class divide in this country that is worsening - so many want to feel "better" than others of their "class" so they join in with the richer tiers' scapegoating of the poorer sections of society. Working class snobbery is one of the biggest scourges out there, it causes people to disregard a fair and just society and believe poorer people are mostly always workshy, and deserve what they get. Cameron can do what he likes in terms of benefits cuts he will get a lot of backing for it
I truly believe if a plan was put forward to cease all benefit payments and introduce workshouses again (albeit dressed up to sound different to the standard image of workshouses) so all those benefit claimants couldn't get council accommodation or indeed any private accommodation, then that plan would garner more support than expected out there.
The Tories "Model of Chaos" politics works. Create race and class war, bring division amongst the working classes pander to the I want what they have next door and more, why should they have anything beast that lurks out there, and they'll be able to carry on with decimating the poorer working class quite happily