The answer to your question is False.
As to the problem of denial of warranty for the repair what you have to consider is that manufacturer has right to refuse repair to an affected part due to modification.
The Tuners understand this
WILL A PROTUNE VOID MY WARRANTY?
Our custom tuning is created as a file which is loaded on the Cobb AccessPort and then flashed on the vehicle's engine computer through the OBDII port. In case the car needs to be taken into service it is highly recommended to uninstall the Cobb AccessPort from your car by plugging it in and simply choosing uninstall from the menu options. The process is virtually effortless and takes only a couple minutes to complete after which the car is restored to the original software before Accessport was installed. This functionality is provided by Cobb Tuning and their AccessPort device. In case of any issues with the Cobb AccessPort device please contact Cobb Tuning directly.
Some dealers are friendly to performance modifications and it's usually known which are not by the local enthusiasts. Occasionally a manufacturer will tighten the screws on dealers that are performance mod friendly by denying warranty claims.
I've chipped a TDI before and I did it after warranty was up since the local dealers were known to check for altered ECU and software. I accepted the fact that it was putting my powertrain warranty at risk.
Manufacturer can't refuse to warranty equipment unaffected by the modification. Example is if you change out the wheels to larger than oem spec and the struts fail then your on the hook, if your radio fails then it still has to be covered under warranty.
If you disagree with dealer or manufacturers determination then you still have right to go to arbitration or court dependent on provisions in manufacturers warranty and documents you sign before the dealer works on your vehicle. Often anymore you have to go to arbitration.
Merchants in the business of selling tunes and other performance modifications often reference the Magnuson-Moss Warranty Act to allay concern about vehicle warranty and get a sale of their part/service. Reality is there is little to no protection from this warranty act until you are in court.
As stated earlier "Don't mod vehicle until warranty is expired".