Interpolation problems aside, you'd be much better off writing this as a single call to perl on the other side.

my @result = $telnet->cmd( qq{perl -MPOSIX=strftime -lane 'BEGIN{$date
+ = strftime( "%Y-%m-%d", localtime );} print $F[3] if $F[3] lt $date'
+ /data/pinpe.csv} );
[download]

(Possibly seasoning with the appropriate -F, argument given the file extension; see perlrun for more details on autosplitting.)