Because speech pathologists are generally working with patients that have mental issues, speech issues are generally neurological, and those patients may not have the same emotional self-regulation and self-control as the average person and may act violently.
That said, I wouldn't consider it a particularly "dangerous" job. It's just that, despite the popular discourse, jobs like being a police officer are also really not that dangerous either. When the effect size is small it doesn't take much difference to be amplified in the data. Being a roofer is far more dangerous than being a police officer, even though that's not the typical mainstream narrative, as an example.
That said, I wouldn't consider it a particularly "dangerous" job. It's just that, despite the popular discourse, jobs like being a police officer are also really not that dangerous either. When the effect size is small it doesn't take much difference to be amplified in the data. Being a roofer is far more dangerous than being a police officer, even though that's not the typical mainstream narrative, as an example.