The simple answer is "no". arara's core element are the rules and the specification of the rules inside your main document.
If you want to compile your friend's file with arara you can provide your main testing file like:
% arara: pdflatex\input{file-of-friend}However I think most editors allow the switching between different compilation steps very easy. So if you want to compile with pdflatex you can choose pdflatex.
In my opinion there is no need for such an implementation.