I consider this to be a bug.
It seems the detection routine that ensures the PortableApps packager is not launched from C:\Program Files is flawed.
Any folder name starting with the string "Program Files" on my root is getting blocked, such as "C:\Program Files (portable)" which I had just created to store all my portable apps.
From my reading of https://portableapps.com/node/33575 , there seems to be legitimate reasons to block "C:\Program Files" and I guess "C:\Program Files (x86)" as well on x64 systems.
However, IMHO, the package should not block a folder that is not a system folder even though it has "Program Files" as part of the name. I should be able to use C:\Programs Files blablabla" or whatever variation of my choosing.