What are the advantages of doing this over using a fhir server?

Look at the parameters you can pass to the use command - the below will do what you want

u $i:(:"+S")

read password

or  if doing directly at the command line instead of from a called routine

u $i:(:"+S") read password 

Check whether the tstart command is issued with a post conditional parameter   if so then you may be able to make the ts fail and therefore the ts would not start the transaction. 

For instace if you had:

Tstart:$g(^startts)=1

Then killing ^startts would cause the transaction not to be created.

#longshot