What is the meaning of this statement? [closed]
The context of the quote, found here at Google Books is that inmates who are not eligible for certain programmes may enrol on them in order to access benefits offered for enrolment, if the benefits are a tradeable commodity.
In this instance being discussed the programme is a Suicide Prevention Programme and the incentive for enrolment is two Mars Bars. As Mars Bars are valuable currency, lots of people will declare themselves to be contemplating suicide in order to enrol and get the Mars Bars.
'Everyone would be bloody suicidal' is a metaphorical expression of the fact that many would pretend to be suicidal.
In the Google book link you will also see a snippet of a non-viewable page which seems to suggest that the term ‘screw’ covers both uniformed and other staff, so including the staff who run programmes for inmates.