No. When the docs say 'unshift can take a scalar EXPR', they mean as the first argument, eg:

my $ref = [ 2, 3 ,4 ];
unshift $ref, 1;
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But that's probably too much information. What you need to understand is that the standard (non-experimental) syntax for unshift is:

It so happens (as is often the case) that the LIST that you want to add at the beginning of your ARRAY consists of just one element (namely 'Top').

Maybe the doc for unshift could benefit from a less obscure example of usage?