Just saw that the ad for this was reposted. Now the position has gone from a 2 year visiting post to 1 year. Really? I'd like someone explain to me how it is reasonable to advertise a position originally for two years and then switch it. Note that they haven't interviewed anyone, but this is still suspicious. When were they going to tell applicants who are already in the system??
It sucks, but what are they supposed to do if the university yanks the funding / changes the situation on them? This happens to TT jobs, too! The fact that they hadn't interviewed anyone makes it pretty innocuous. Much better they change it now than at the last minute or after the person has been working there a while.
your reaction makes sense. a 2 year visiting contract is a sweet deal because you get a little breather with applying for jobs and can focus on your research a little more clearly. one year means starting up with classes and getting those applications out again asap. on a very practical level though it only matters to the applicants who they decide to interview. would a one year contract be a deal breaker? on the institution's end there's probably no compelling reason to spend time updating all the applicants, even if it's just an email blast.
at the phone/skype interview it would be reasonable to ask how does this position fit the department's needs/contribute to the curriculum? that might be the ice breaker question to help you find out how likely it is that they might need someone the following year. if there's a reason why the 2year was especially appealing to you, like a research opportunity or collaboration that you could do there in that time frame, then maybe you bring that up too.
they might even share some context during an interview. it could be that someone made an error in the job text (oops! that was supposed to one year not two!), or funding/leaves changed and the dept only has approval for a one year contract (and is already planning the request for next year's needs), or something else.