Earlier quoted context omitted.
Actually I think it highlights how well Apple manage their message and keep people focused on them: most people probably don't notice or actually care about the difference in latency, and 9ms is not the best in the market, yet it becomes a 'good news story' validating Apple
Latencies bellow 16ms require a refresh rate higher than 60Hz. For 9ms you need at least 90Hz. Don't know many who do that. Specially if you take in consideration the battery hit that the faster update rate requires.
In the worst case 60Hz + this new pen will add up to (16 + 9) 15ms of latency, right?
If the screen refreshes at T=0,16,33,50 and you create input at T=8 then the input will be processed at T=17 (8+9), so you will need to wait for T=33 before it show up for a total latency of 25ms (33-8).
Which is a lot better than the potential total latency of 36ms with a 20ms pen.