On first launch, it downloads a copy of the last version that supported portability — that was DropBox 1.1.45.
I observed the same at my end...
Not really sure if older Dropbox versions are a security liability; IMHO they have just been adding new features since the version DPAHK uses. For instance:
* Fix missing translations.
* Fix importing of files larger than 2GB on OS X.
* Better handling of the "never from this device" option on Windows.
* Fix for infinite syncing on really really long paths.
1.4 (Codename: Phoenix Down) Features
* Importing of photos from cameras, phones, and SD cards.
* Batch upload/download of files.
Still, if you're concerned with the security of DropboxPortableAHK, its options and execution can be locked by setting a password
(not your Dropbox folder, mind you; if you want that, you'll have to encrypt it yourseld; I suggest using TrueCrypt
to create an encrypted volume...). YMMV, though...