Where exactly does it say that? I don't believe you.
Here is page 11 from the ProPlus manual.

The page clearly says in the first paragraph that the ProPlus displays a bar graph at the bottom that is a display of the air time remaining....based on current consumption rate. So if you keep breathing the same way, at the same depth, that is how much time you have left. Go deeper or breath harder/faster, you'll have less time; go shallower, you'll have more time.
The second paragraph describes the numbers in the middle of the screen: "Dive Time Remaining." there are three things than can limit your dive time: air available, N2 buildup, O2 buildup. Whichever of those is smaller will be displayed. So if you are fairly deep and breathing relaxed, You might (example) have 10 minutes left before your N2 limit (NDL), but 20 minutes of gas left, and 120 minutes of O2 time left. The display will then show 10 minutes. A shallower dive with less N2 biildup might instead show the amount of gas left, because N2 is no longer limiting your dive. In this case, the numerical display and the bar graph at the bottom would show the same number.
But your gas consumption is NOT used to calculate N2 buildup; that is a function of depth and time only. "Air time remaining" is NOT the same as "Dive time remaining." they mean different things and are calculated in different ways....but in some situations might be the same number.
The problem is you guys are saying different things without being clear on your terms. When mstevens says "bottom time" he means NDL, based on N2 buildup. You are interpreting that as "dive time," which is the Oceanic term for whichever is smallest of N2/Bottom time, air consumption-based gas left, and O2 buildup.