On the to young page, create a session variable:
use the Cookies toolkit Set Session Value Server behavior. On the Server behaviors panel, Click the Plus Button and select WA Cookies -> Set Session value.
Use the Before Page Load trigger, set the name to "lockout" and the value to "yes"
Then using the SecurityAssist access rules manager, Create a new rule. Go to Modify -> SecurityAssist -> Access Rules manager.
Set the Restrict option. Click the Lightning bolt next to value and select the lockout session variable. Select Equals for the comparison and type "yes" in the compare to box.
open the page you wish to restrict access to and Click the Plus button on the server behaviors panel, Select SecurityAssist -> Page Access. from the list select the rule you just created and select a page to redirect to.