I can’t tell you if there is any way to link the keypad to the Blink system, but maybe that can be done via IFTTT?
Either way, what I can tell you is that if you use the geo location service from Life 360, in IFTTT, then it will work a treat.
It was suggested to me by @marktheknife for the same reason you stated, the native IFTTT geo-location is unreliable at best. Useless is how I would describe it. On complaining about it he mentioned that Life360 works very well, and this has proved to be the case for me.
I think he uses a further different location service now, that also works well, but I don’t recall the name.
Anyway, build a couple of quick applets, to arm and disarm, utilising a location created in Life360, and I think you will be pleasantly surprised.