Hello, mac analyst here.
I tried to install the mentioned application but my Avast (with the latest virus database) hadn't blocked anything.
My guess is that in your case, the issue could be caused by an interaction between our AV and the adware removal app.
In particular, Dr. Safety could have found a malicious file (possibly in an archive which is not scanned from the inside by Avast) and after it unpacked it for inspection, Avast detection was triggered.
So, it probably wasn't Dr. Safety itself that got blocked.
Anyway, as others already pointed out: In general, it is not a good idea to install more than one security solution to your system.