I had to look that up too.
Yeesh, gettin' old sure is a bummer, am I right?
At least we all can like Geno, regardless of our ages. He is timeless!
Honestly, it might work just like WFT's charge move--You don't get any bonus unless you time it right at the finish. This would mean in order to get the bonus, you literally HAVE to ride out the whole move's duration, making it unsuitable to spam, especially on the ground. You'd go flying up into the air every time you wanted to boost, lol.
It would also mean that if you wanted to snap to the ledge, you'd lose the bonus opportunity. That way, you have to decide if you want to just grab the ledge safely, or take the riskier option and get a boost.