This simply means that while the early access is going on, the price will be slightly lower than the completed product.
And, of course, there is a cap.
The reason it was worded like that was because when I wrote it the way I did just now, Steam didn't approve my page and asked me to change it to something similar to what you screenshotted.
And by the way, even if it was true, raising the price just means that there is a benefit to buying it early. I don't see any different between this and giving a discount that will expire after some time.