In scan progress options in policy you selected do not show
scan progress .So user will not be able to see scan progress or pause/snooze the
scan.Try by giving show scan progress and try…

According to administraton guide you have to select Showscanprogress

or Show scan progress if risk detected for using scan/snooze option.From pge no 435 of admin guide” To configure scan progress options for
administrator-defined scans

1
On the Antivirus and Antispyware Policy page, click Administrator-defined

Scans.

2
On the Advanced tab, under Scan Progress Options, click Showscanprogress

or Show scan progress if risk detected.

3
To automatically close the scan progress indicator after the
scan completes,

check Close the scan progress window when done.

4
Check Allow user to stop scan.

5
Click Pause Options.

6
In the Scan Pause Options dialog box, do any of the following actions:

■ To limit the time
that a user may pause a scan, check Limit
the time the

scan may be paused, and then type a
number of minutes. The range is 3

to 180.

■ To limit the
number of times a user may delay (or snooze) a scan, in the

Maximum
number of snooze opportunities box, type a number between

1 and 8.

■ By default, a
user can delay a scan for 1 hour. To change this limit to 3

hours,
check Allow users to snooze the scan for 3
hours.

7 Click OK.”

So, what is the difference between, stop, pause and snooze in these settings?
If they have the option to "stop" the scan, will it start up again at the pause interval or is cancelled til the next scan date?
It seems that if you do not check off the ability to stop it, they can't snooze or pause it either.

We don't want the user to be able to stop it for good, just pause it temporarily if it is slowing down their machine during a critical task.