The magnitude of the charges are derived from the Milikin oil drop experiment .The charge of electron was derived but in order to make a atom electrically neutral ,we assigned same charge magnitude to the proton .
If you look at the arithmetic, yes you are right. The electron has charge
Having said, there appears no physical significance of the statement so far as Coulomb's Law is concerned.
Coulomb's Law sates that the force between the two charged particles is directly proportional to the product of the charges. The difference between the charges does not count.