Chances are, not very good, unless he has SNAP, but even then he will probably have a 50-50 chance.
Construction Management at RMIT is essentially a bachelor of applied science specializing in construction management, you might want to put applied science as one of his prereq's and if he gets into that then he can to do for half a year or so and then transfer into construction management, given he gets a high enough GPA. It doesn't need to be applied science and it doesn't need to be at RMIT, as long as the course has some relevance to construction management.
Furthermore, do you also happen to know of any other construction/ building related University courses which require an atar that is similar or below to the one he has achieved?
I could't find any, the only ones were too high atars or ones that required a portfolio of the sort, although there was a similar one at Deakin but that is based in Geelong. Not sure if you're interested but anyway the info is in the link below if you are curious:
http://www.vtac.edu.au/CourseSearch/searchguide.htm?courseCode=1400416101