No, that's not right. In single quotes, the backslash escapes do not apply (backslash only escapes the ' character). Had he been using double quotes, tabs would have been interpolated for the \t sequence.

Try it:

> perl -de 1
Default die handler restored.

Loading DB routines from perl5db.pl version 1.07
Editor support available.

Enter h or `h h' for help, or `perldoc perldebug' for more help.

main::(-e:1):   1
  DB<1> $x = 'c:\tab'

  DB<2> p $x
c:\tab
  DB<3> $x = "c:\tab"

  DB<4> p $x
c:      ab
  DB<5> q
[download]

The most likely cause of the problem, as others have pointed out above, is that the script doesn't have permission to read the file it's trying to open, but the error is not being trapped.