As DeeDeeCues stated differently in post 21, you got the first sentence correct but you got the second sentence incorrect and in fact exactly backwards.
What affects deflection is the mass (weight) in the first six inches of shaft or so, with heavier weighing material causing more deflection. In most cases the leather cue tips are lighter than the shaft wood and ferrule material. So think of it this way. With a long tip, in that first six inches of shaft you have say .25 inches of tip (which is 4.2% of those first six inches), one inch of ferrule (which is 16.7% of those six inches), and 4.75 inches of shaft (which is 79.2% of those first six inches). With a short tip however, in that first six inches of shaft you have say one eighth inch of leather tip (2.1%), one inch of ferrule (16.7%), and 4.875 inches of shaft (81.3%). So with a long tip more of those six inches is a lighter material (4.2% compared to 2.1%) which in turn serves to lessen deflection since the overall weight of the first six inches decreases with a longer tip. As you shorten the tip then more and more of those six inches becomes heavier wood instead of leather and so the deflection naturally increases because the weight of those first six inches increases.
It is even more than that though. All of the six inches do not count the same. The closer it is to the tip of the shaft, the more that weight matters and the more it will affect deflection. Put another way, increasing the weight in the first quarter inch of the shaft will increase deflection more than if you had increased the weight in the second quarter inch by the same amount, and the second quarter inch back from the tip makes more difference than the third quarter inch back does, and so on all the way back to six inches back from the tip where added weight is having substantially less affect than it does when added nearer to the tip. The nearer to the tip you add or remove the weight, the more difference it makes to the deflection, and in the case of trimming your tip down short you are in effect increasing the weight where it matters the very most, in that very first quarter inch. Plus by shortening the tip you in effect just moved the heaviest material of all, the ferrule, even closer to the tip end by shifting it forward where it will now have slightly more affect on increasing deflection than it did when it was slightly further back.
Now whether shortening the tip from say a quarter inch to an eighth of an inch and shifting the ferrule slightly forward creates a meaningful amount of increase in deflection is debatable, but it definitely increases it because you are in effect replacing lighter leather with heavier wood as well as moving the heaviest ferrule material more forward. I would call it a reasonably inconsequential amount of deflection change in the scheme of things but somebody else might be a bit touchier about even small amounts of deflection increase and see that same amount as being much more substantial so to some extent it probably depends on how touchy one is about any changes in deflection.
For the record, the fact that every quarter inch of that first six inches than you can lighten up in some way makes a difference in reducing deflection (especially the nearer to the tip it is) is the reason that there has been a trend in making ferrules as short as possible instead of nice and long like they all used to be because wood is lighter than most ferrule materials and so the more of that heavier ferrule material you can get rid of the less deflection you will have.
