I think the leverage that Stargaze is referring to is right-left leverage to steer, which is easier with longer stems (though not as quick).
But I think Stargaze is supporting his a larger than common proportion of his weight his arms on his road bike bars. What is the need to do a TT position properly? The UCI have outlawed TT positions on road bike bars (e.g. see
Alexandar Richardson's dismissal from the Tour of Turkey) because, I think, it can reduces manoeuvrability in a peloton but road bike bars provide superior braking and handling to TT bars, so a TT position on road bike bars is a good alternative or compromise when riding alone on roads with cars.
I only stopped doing it because my knees started to hurt due to weak butt muscles and the need for a major glute workout, which can be achieve by more old fashioned pedalling methods.