[HakujinGrande]

Okay, with the corrections from CA 2003, you are correct, but not for the right reason.

Going just off the wording of the codex, and ignoring the correction for the sake of argument:

Just because the options section does not list not taking a heavy weapon, does not mean is is not a valid selection.

For an example, the Space Marine codex, in the Options section (just like the Options section of the Wraithlord) of the Tactical Squad states:

"The squad may be equipped with frag grenades at +1 point per model and/or krak grenades at +2 per model."

There is no mention of an option of not taking grenades, so by your logic, each Tac squad would be forced to take grenades of at least one type.
Same for the Command, Scout, Assault, Bike, Scout Bike, and Devastator Squads.