Yes, the crop being empty is a good thing

IF a crop is not emptying properly, if it's turned sour, etc., sometimes the contents may come up and the bird can aspirate fluids - this can could cause some sneezing or even aspiration pneumonia - it's always a good idea when you have one that is not feeling well or you have a concern to check crop function.
Since she's "new" it's good that you are keeping her separated - sneezing can be from a number of things - but if it's fairly frequent and consistent and there's no other explanations, then the likelihood of respiratory disease is greater. There are several common respiratory disease that chickens have - Infectious Bronchitis, Mycoplasma, ILT and Infectious Coryza. In CA there have been outbreaks of NewCastle as well. Antibiotics can treat
symptoms of bacteria-like disease (Mycoplasma and Coryza) and will help with secondary infection of viruses (Infectious Bronchitis and ILT). Birds are still carriers of the disease even when recovered.
http://edis.ifas.ufl.edu/ps044
If the symptoms worsen, then getting some testing would be a good idea - a lot depends on your goals - having a respiratory disease in your flock, you would want to keep it closed - no selling of hatching eggs, chicks or showing chickens.