On the face of it, that’s what the article appears to say, but per the following section in it, I believe that this applies to tickets bought directly from UOR:
Promotion tickets, third-party vendors
Everything I’ve written here applies to tickets purchased directly from Universal Orlando. We also know that, in most cases, you should be able to upgrade tickets purchased from popular third-party vendors like Costco, AAA, and Undercover Tourist. However, if you purchase from a third-party vendor, you have to be very careful, as some tickets from third-party vendors cannot be upgraded. Your best bet is, if you think there’s any chance you might upgrade, check with the vendor before making your purchase.
The other thing to be very careful about is promotional tickets. For example, if you win tickets from a radio station, you likely won’t be able to upgrade these.