This is NOT CORRECT AT ALL.
How could suboxone choose what effects to turn off and what to turn on? It can't. If it blocks the site, the other opiates are NOT ACTIVE, thus you can't overdose on them.
You can take an infinite amount of opiates on top of suboxone and you will never put yourself into withdrawal. The rule goes you can take dope after subs, but not subs after dope.'
The reason for the withdrawals in the first place is because if a person usually needs 100 receptors filled to be high, and takes 100 receptors worth of heroin, then takes 100 receptors worth of bupe, the bupe which has a higher affinity will bump the H off the receptor site, and bind to it. This would lead to 100 receptors filled with bupe, however since bupe isn't a full agonist, for purposes of this example, we will pretend that only 50 receptors are active. The other 50 are filled, but not active. Since you need to have 100 receptors filled, but now only have 50, you will not get high. If you go into withdrawals anytime when you have 60 or lower receptors filled, then you will go into withdrawal. However, if you went into withdrawal any number of 40 or lower, at this dose, even though you are kicking out the H for bupe, you will just be less high, however, you will NOT be in withdrawal.
It would take a great deal of opiates to cause liver damage. So if the other opiates arn't binded to the receptor sites, then they will just float around, and then be eliminated, a person's body is NOT loaded up near overdose.
However, if the sub were to wear off, while there was still a sufficient amount of h in the bloodstream, then you may have that take over, and could have an overdose. (For example you have 100 receptors full of suboxone, you need 100 fill to get high, and you take 110 worth of H while on bupe. If the bupe wore off completely while all 110 worth of H was still around, you would be 100+ receptors, and potential overdose area).