How to pull Triac gate to ground with an NPN transistor with AC present
You could use the transistor to switch a small relay. Or use a MOSFET-output SSR. Both those solutions also avoid any issues with where the grounding is.

As this is apparently lifted from a patent for a safety device - if your application is similar be sure to undertake a proper engineering review of the safety aspects. Keep in mind that semiconductors most typically fail on (but can also fail off or the connections can go open).

Edit: I am suggesting you replace the switch with the SSR- 400V or 600V units can be found, such as the TLP797J. You have to confirm that the voltage rating is adequate. This particular one can switch 100mA. 

In the case of the relay you can choose whether to use a normally open or normally closed contact of a sealed SPDT relay, and replace the entire circuit. I assume they didn't do that in the patent for some reason (perhaps just the wiring) and I would want to figure out exactly why.  

Again, the safety aspects need to be examined carefully at a system level as well.