The data is encrypted using two way TLS and the traffic is sent (without any processing or storing, or transmitting to third parties) to devices you have synchronized.
Your fear is probably not atypical, and as an indie dev it's maybe my biggest obstacle for this app's success. With that said, my number one priority for users is data security. I spent a great deal of time working on the security aspects alone, and if you have any questions about the details please feel free to contact me-- my information is available on the website linked.
EDIT: more clarity (I hope)
Can we remain sure that no data is sent otherwise?
As well: being able to launch a command on specific events would be nice for us hackers (if it's not already there, didn't check yet in depth).
Thanks for the idea about launching on specific events, I will definitely look into putting this in a future release :)
PS: you could "market" the fact that no data is sent a bit better, maybe have a big switch in the setup that makes the current config clear (with bold "no data sent" by default etc). Hope this helps!
EDIT: Also, raise your price!