Other than the fact that Curtius has just finished narrating:
The rejection of Perdikkas
The rejection of Herakles
The rejection of the unborn Alexander IV
This, of course, leaves only Arrhidaios as the sole heir and the only one acceptable to the Macedonian rank and file. Simple really.
A little too simple really. You have rather overlooked the fact that despite 'rejection' as candidates to succeed to the throne, 'Heracles' and Alexander IV are still
technically heirs by birth to AtG, and Arrhidaeus cannot be truthfully described as "sole heir" in Paralus' version.
But Arrhidaeus is
said to be “solus heres”/sole heir, and again at [X.7.6], he is "the only one born to inherit/hic solus est”, and at [X.7.2] no-one
but Arrhidaeus has a claim as "next in blood", ['Heracles', if he existed, was not only "next in blood", but a son to boot, and therefore also had a claim and was born to inherit] and that no-one but Arrhhidaeus could assume Alexander’s name, or the family name.[Heracles could not assume his father's name? Arrhidaeus ( who was just as 'illegitimate' in modern terms) did so, becoming Philip.][X.7.15]
All this denies the existence of Heracles, and strongly implies the speech attributed to Nearchus is an inserted later interpolation.
Also, Curtius brings back Perdiccas as a candidate [X.7.12], but the majority favour Arrhidaeus because he is "the Royal stock" ( and Heracles is not?) - but no mention of Heracles, who in Paralus' version, still exists.
The short reference to Heracles is simply inconsistent and incompatible with the subsequent narrative text - the sign of a careless interpolator.
Paralus' line of reasoning considers only part of the evidence, just as earlier when he claimed that the lack of mention of Heracles in the epitomised sources was because epitomators 'left things out' rather overlooks the obvious corollary that they don't mention Heracles because he wasn't mentioned in the original text in the first place.Since we can't know which, this no evidence at all.