I would be careful about clearing the c spine of an intoxicated individual, both Canadian and NEXUS c spine rules don't include those under the influence.
I imagine, the "clearing" the cspine was just a poor choice of words for not using a backboard.
I have seen several studies over the years, and with a bit more understanding about anatomy and physiology than was known in the 1970s, I really think the backboard is jst another one of those flawed EMS treatments that are not going quietly into the night.
In other news:
a 20 y/o female isn't exactly in the high risk category for ACS.