I think the key here is to find out how the degree is titled compared to non-distance learning Australian degrees and then compare those to the American degrees both distance and non-distance. Some US schools have distance learning degrees that indicate on the degree that they are distance degrees. Some schools do not. From my experience, employers like to see traditional degrees (school is less important) not distance learning degrees. So, they may take a candidate with a traditional degree from a lesser known school over a distance degree from a better known school. Of course, that begs the question, would an employer rather have someone without the master's or someone with a master's from a distance learning program.
I will say, though, that it also depends on the field too. I think the perception is changing slowly but I think there is still a little bias out there. This is a very tricky topic because the market is so tight that employers use many factors to rule out or enhance a candidate. School reputation is certainly a factor. My degree is from a school on Long Island. Because local employers know the reputation of the school they like to see that school on a resume. When I've applied for positions outside of New York, they don't care as much about the reputation of the school but they like that it is a private school in New York. So in your husband's case an American employer may like the fact that he has the master's degree above or more than the reputation of the school and/or the fact that is a distance degree. An Australian employer may like fact that you have the degree from that specific school and it doesn't matter that it was obtained in a non-traditional manner.
I hope what I'm saying is making sense. I've spent so many hours going over all of the ins and outs of this sort of thing and it can get confusing. I think ultimately it is better to have the degree than to not have it. As long as the school does not have a reputation of being a financial aid mill.