To get Emacs to exhibit this behavior, select PERL / "Mark Function". Then PERL / "Indent Region". I spent a little time in Google and found this little gem:

+;;;  (`cperl-fix-line-spacing'): Allow "_" in $vars of foreach etc. w
+hen
+;;;                underscore isn't a word char (gdj-contributed).
[download]

So I added this:

;; Allow "_" in $vars of foreach
'(cperl-fix-line-spacing)
[download]

to my .emacs file, but apparently its not doing what I expected because variable names in a for loop with an underscore still get "split". Feels like I'm on the right track, but sometimes EMACS behavior is a mystery to me.