I can see why the prosecution was a little shakey but honestly I think they should have gone forward with the case as far as they could unless the woman reversed her story. I mean rapes are already massively underreported and these cases where the prosecutor backs off because he doesn't trust the victim just makes other victims less likely to come forward.
Now of course he shouldn't try to engage in legal schinanigans or use unreliable experts or tainted police line ups in order to make sure the guy goes to prison
but just present the facts and let a judge or jury rule that the case is insufficient.