It's not paranoia, but although a serious weak point on a lot of cars, to be honest a waste of time with a Volvo.
The breach works by allowing devices to access the immobiliser and key programming routines, and either code a new key or fool the car into thinking that a legitimate key is present. Due to Volvo security, they would also need to brute-force crack the CEM which would take a few hours minimum.
I'm retired now, but worked for the police dealing with vehicle thefts for many years. Never known a Volvo not fitted with keyless start to be started and driven without access to an original key, and although keyless start can be compromised it involves a different method to accessing the OBD port.
Things can change though. There are teams of hackers in eastern Europe and the far east in particular, who spend all their time working on bypassing vehicle security systems and manufacturing the kit to do it
