Is it safe to use twitter as the communication-way for controlling your PC?
Yes and No.
This always depends on what the user does.
For example, if someone uses a weak password
or doesn't keep it secret
, then everyone can
control your PC!
Also you should make an own account
for the controlling of your computer and you should
make the tweets of this account private
shown in this video!
If you don’t make your tweets private then everyone can see and search answers of TweetMyPC which can contain information you shouldn’t publish (like ip-address, links to screenshots …).
But if you follow these rules then – yes, it is safe.