Suppose you pick two people at random. From one, you pluck a single hair from their head. Is it possible to tell who had the hair plucked by weighing the people?
Technically, plucking a hair makes a person very slightly lighter, so you get a tiny bit of information about who had the hair plucked by weighing the people. But the information is very slight because the effect is so small that for practical purposes it may be ignored.
Similarly, heavier objects are mathematically predicted to collide with Earth very slightly faster because of their gravitational effect on the Earth. But the effect is so preposterously small as to be meaningless, so it commonly ignored.
The answers you linked don't disagree with each other. One isn't right and the other wrong. They simply need to be interpreted in their own context. People don't try to account for every little possible influence, like whether a hair was plucked from someone's head or whether they've trimmed their fingernails recently when talking about a human's weight. Similarly, they don't always try to account for every tiny phenomenon and make every statement perfectly precise when they talk about physics.