I’m not sure who “they” it is you are referring to, or the exact quote that you are referring to, but I purchased Sublime way back in the Sublime Text 2 days as well (before 2014), and it was very clear that the license was for the entire ST2 series. When ST3 came out, I had to buy a new license or stick to ST2. Now that ST4 has been released, a new license is requrired (granted, terms of the license are now a bit different for Sublime as of ST4, but a license is still required for the new version(s), etc.).
Yes, your ST2 license is always valid for all ST2 versions, that should not have changed. And if you had a license for ST3, it should be valid for all ST3 versions. It was never promised it would be valid for any future, major versions, just minor versions and bugfix versions.
Now, if your ST2 license has stopped working for ST2 versions, then you should contact support as maybe your license has somehow been leaked and banned. I’m sure they can correct it for you.
If you are complaining that your ST2 license does not work on ST4, then your license will not be valid, though I would be surprised that you didn’t notice this when ST3 came out years ago as it also would not allow an ST2 license.
With that said, people who bought an ST2 license very close to the ST3 release were allowed an auto-upgrade to ST3. I don’t recall the year ST3 came out, so maybe your purchase matched up with that timeframe. But it had always been clear that a license would not be for every release under the entire lifetime of Sublime’s development, only for the major version under which the license was purchased (see Sublime Text’s new terms for ST4).