Except that the rules explicitly refer to allowing a smartlinked character to make use of those commands. The Smartlink is required.
I suggest you read the description of the Smartlink Vision Mod again...
All
bold text in quotes are emphasis from me.
Smartgun System: The smartgun system connects a firearm or
projectile weapon directly to a user’s smartlink (p. 333). It incorporates
a laser range finder and a small camera, and keeps track of ammunition,
heat buildup, and material stress. It allows a smartlinked character to
mentally switch between gun modes, eject clips, and fire the gun without
pulling the trigger. The camera allows for targeted shooting around
corners, without exposing oneself to return fire.
The system makes use of advanced calculation software, allowing
the user to aim even weapons with a highly ballistic firing arc (like
grenades) with tremendous precision over any distance. The smartgun
system can also be accessed via wireless link, allowing for the gun to be
remotely fired or to block the trigger (in case an opponent gets ahold
of it). When used with a smartlink, it provides a +2 dice pool bonus
on the ranged attack test.
Retrofitting a firearm with an internal Smartgun system doubles
the weapon’s price. An external smartgun system can be attached to
the top mount or underbarrel mount with an Armorer + Logic (4, 1
hour) Extended Test. The small camera can be equipped with vision
enhancements (p. 333).
Smartlink: This accessory interacts with a smartgun system
(p. 322) to project the weapon’s angle of fire into the user’s vision,
centering red crosshairs where the user is pointing and highlighting
perceived targets. The smartgun’s laser rangefinder also calculates and
displays the distance to the target. Additional data from the weapon,
such as the ammunition level, heat buildup, and stress can also be displayed.
Requires an image link.
Eject Smartgun Clip
A character linked to and holding a ready smartgun may use a mental
command to eject the weapon’s clip. It still takes a Simple Action to
insert a new, fresh clip. See Smartgun System, p. 322.
The "linked to" is referring to a connection to a smartgun through a DNI. You can benefit from the dice pool bonuses of a smartgun system without any DNI. You still can see the AR displays and the projected arc of fire and so forth, gaining the bonuses without have a Direct Neural Interface, so long as you have a vision augmentation of some sort giving you the information.
You only need the DNI to gain the added bonuses of being able to
think commands at your gun. The bonus speed of some actions (eject clip, change fire mode, etc) related to the Smartlink are gained from the DNI allowing a user to send commands via commlink to gun equipped with a smartgun system. This is similar to being able to send messages via commlink:
Speak/Text Phrase
Speaking one phrase or sentence of verbal communication is a Free
Action. If the character wants to speak more, each additional phrase/
sentence requires a Free Action. The gamemaster should be careful
to control excessive, unrealistic conversations within the span of a
Combat Turn (about 3 seconds). Some gamemasters and players may,
however, prefer elaborate communication.
Characters who are equipped to send text messages through a
neural connection with their commlink may also send short messages
as a Free Action.
Think of the bonus free action commands "provided by a smartgun" as the result of sending a message through your commlink
linked to your gun to the smartgun systems, telling it what to do.
