While it is pointing out the reader into some general directions, the general nature of answer https://physics.stackexchange.com/a/70858/139287 is in my taste too much handwaving. My personal perspective on this problem is as follows:
First, let us describe the particles move further apart by a formula. We can do this as follows: Let $l(t)$ designate the (non-zero, non-directional) distance between the two particles at time $t$. Now define the formula $B(t_1,t_2) :\Leftrightarrow t_1 > t_2 \Rightarrow l(t_1) > l(t_2)$. If $\forall t_1, t_2: B(t_1,t_2)$, ie. if $B(t_1,t_2)$ holds for all times $t_1$ and $t_2$, then we will call this particles move further apart.
In the experimental scenario before the C, P, T transformation, this is the case.
Now let us do the C, P, T transformation. It has no effect on the definition of $l$ but it transforms $B(t_1,t_2)$ into $B(-t_1, -t_2)$. So after the transformation we are interested whether $-t_1 > -t_2 \Rightarrow l(-t_1) > l(-t_2)$ holds for all $t_1, t_2$. This is the case. So after the T transformation the particles still move further apart.
To see the latter claim formally, you might want to apply some laws of logic. To see it informally, let us have a look at an example.
Let us chose in the situation before the T transformation the values $t_1 = 1$ and $t_2 = 0$. The precondition of the implication holds, $1 > 0 $, and the conclusion also holds, $l(1) > l(0)$. We know this, as in the situation before the T transformation the particles are moving further apart.
Now let us have a look at the situation after the CPT transformation, where the CPT theorem tells us that the transformed property agin holds. Here, let us pick $t_1 = -1$ and $t_2 = 0$. We obtain $1 > 0$ as precondition, which holds, and therefore also $l(1) > l(0)$.
The problem you fell victim of is, in my opinion, an incorrect application of the CPT theorem.
The same mistake has been made in https://arxiv.org/pdf/1103.4937.pdf, where the author argues that the CPT theorem produces repulsive gravitation between matter and anti-matter. In https://arxiv.org/pdf/1108.5117.pdf the problem associated with this line of reasoning is explained in detail. I guess the situation here is similar in nature, although easier to grasp.
Edit: Corrected a wrong use of a symbol.