Xavier
Any assessments that the current rite comes from the West Syriac churches or Coptic is pure BS, having attended ordinations in both there's no comparison. The argument iys false. There may be parallels with original copies of Greek ordinations, which could mean the ordinations are valid, but there's a large corpus of discussion of
how ordinations are done within the Latin Church, but no discussion about making up ordinations from scratch and appealing to something done in another church as if it had some part in why it was composed. There are two arguments in favor
1 The ordination rite was given by 'the church' and the church would fail without priests
Or
2 Throw it into the category of the doctrine of unity
Wherever the bishop appears let the congregation be present; just as wherever Jesus Christ is, there is the Catholic Church. It is not lawful either to baptise or to hold an "agape" without the bishop; but whatever he approve, this is also pleasing to God, that everything which you do may be secure and valid.1
#2 still doesn't answer the question