You need to use the menu->entryconfigure method, like this:

# $item is the item number in the menuitems array
$menu -> menu -> entryconfigure($item, -state => "normal");
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If you initially set the menu option to disabled, when you come to setting $consensus_created later in the code, you can use entryconfigure then to enable or disable (with -state => "disabled") the relevant menu options.

Hope that helps..
-- Foxcub

Update: Clarified things a little.