I could see some edge-cases with each of those approaches.
If there is more than one logged-on user, and both have a “Software\BigFix\Enterprise Console\Settings\ComputerListContextMenuExtensions\Browse Computer”, you might get a “Singular expression refers to plural object” error.
If there is more than one logged-on user, and exactly one of them has the key, you might get a false-negative (fixlet returning False when only one of the logged-on users has the key present).
I would recommend starting instead from the user keys, and seeing whether any user keys exist where the extensions are missing…
q: exists current user keys (logged on users) of registry
A: True
T: 0.023 ms
q: pathnames of current user keys (logged on users) of registry
A: HKEY_USERS\S-1-5-21-123456789-123456789-123456789-10427
T: 0.017 ms
q: exists (current user keys (logged on users) of registry) whose (not exists keys "Software\BigFix\Enterprise Console\Settings\ComputerListContextMenuExtensions\Browse Computer" of it)
A: True
T: 0.023 ms
q: pathnames of (current user keys (logged on users) of registry) whose (not exists keys "Software\BigFix\Enterprise Console\Settings\ComputerListContextMenuExtensions\Browse Computer" of it)
A: HKEY_USERS\S-1-5-21-123456789-123456789-123456789-10427
T: 0.030 ms
In ActionScript, we could use the following in a createfile or appendfile command to build a batch file, containing the one or more REG commands we need to run to create the keys and values. Here’s the start of an example
q: concatenation "%0d%0a" of ("REG.EXE ADD %22" & it & "\Software\BigFix\Enterprise Console\Settings\ComputerListContextMenuExtensions\Browse Computer%22") of pathnames of (current user keys (logged on users) of registry) whose (not exists keys "Software\BigFix\Enterprise Console\Settings\ComputerListContextMenuExtensions\Browse Computer" of it)
A: REG ADD "HKEY_USERS\S-1-5-21-123456789-123456789-123456789-10427\Software\BigFix\Enterprise Console\Settings\ComputerListContextMenuExtensions\Browse Computer"
T: 0.174 ms