The system seems to be a cover with no connection with the phone itself. It relies solely on the internal accelerometer so basically it can trigger the deployment if you jump or find yourself in any 0G situation even for a short period of time (it looks very sensitive anyway).
What if you drop it at night?
Phones have pocket detectors already. They use infrared distance sensors mostly.
...and the complexity increases by orders of magnitude. With all the decision logic, the added latency might register as "drop...thud...oh hey, weren't we supposed to deploy something?...legs deploy"
I think you grossly overestimate how much latency another variable to the decision logic would add. Keep in mind that this is computed onboard, not by bluetooth to the phone or anything. So it can be done by a dedicated chip checking 100 times a second if accelerator value ~= 0G and a proximity sensor detects nothing.
The previous comment noted that "phones have [suitable sensors]". Duplicating those in the board would work, but even then - checking every 10 ms will mean a far higher battery drain (and yes, we've just complicated everything at least one order of magnitude, this point still stands).
Not reliable enough for a mass production solution.