In my opinion, this was a justified encounter, with a few avenues of escape optioned to us during the scenario... had we chosen to "try to find the sniper" we would probably have all died... we didn't do that... we ran our shadowrunning asses off, and vacated the area... this is what any shadowrunner should do when confronted by this type situation... leave the revenge for later when you can regroup and find out who the shooter is... there is a time for fight and there is a time for flight... hopefully you can recognize which is which...

And here's the flip side of that situation. If there was no sniper and it was just a SWAT style team that shot you up, you probably wouldn't be wanting revenge against the remaining living SWAT members. They're impersonal, that sniper made the encounter personal.