This is your personal interpretation. The historical fact is another and Demosthenes said it clearly:
"...οὐ μόνον οὐχ Ἕλληνος ὄντος οὐδὲ προσήκοντος οὐδὲν τοῖς Ἕλλησιν, ἀλλ᾽ οὐδὲ βαρβάρου ἐντεῦθεν ὅθεν καλὸν εἰπεῖν, ἀλλ᾽ ὀλέθρου Μακεδόνος, ὅθεν οὐδ᾽ ἀνδράποδον σπουδαῖον οὐδὲν ἦν πρότερον πρίασθαι."
"...he is not only no Greek, nor related to the Greeks, but not even a barbarian from any place that can be named with honour, but a pestilent knave from Macedonia, whence it was never yet possible to buy a decent slave."
Demosthenes-Third Philippic 31
Not my interpretation. Demosthenes was a mortal enemy of Macedon.
“Demosthenes grew interested in politics during his time as a logographer, and in 354 BC he gave his first public political speeches. He went on to devote his most productive years to opposing Macedon's expansion. He idealized his city and strove throughout his life to restore Athens' supremacy and motivate his compatriots against Philip II of Macedon. He sought to preserve his city's freedom and to establish an alliance against Macedon, in an unsuccessful attempt to impede Philip's plans to expand his influence southward by conquering all the other Greek states.
After Philip's death, Demosthenes played a leading part in his city's uprising against the new king of Macedonia, Alexander the Great. However, his efforts failed and the revolt was met with a harsh Macedonian reaction. To prevent a similar revolt against his own rule, Alexander's successor in this region, Antipater, sent his men to track Demosthenes down. Demosthenes took his own life, to avoid being arrested by Archias of Thurii, Antipater's confidant.“
Again, Macedon genetic affinity to Illyria and Epirus is not only unsurprising but also expected. It would be surprising if they showed affinity to cretans or Greek islanders, or what have you , that should be evident to everyone. Claiming that this affinity to illyrians bothers modern Greeks at all is ludicrous and a strawman. If you think the official greek state cares at all what Iron Age or whatnot Macedon dna looks like you need to get out of the ancient population genetics bubble and step into the real world.
As I said we have evidence that Macedon citizens in classic times spoke Greek (eg the known Πέλλας καταδεσμός ) and even participated in the Olympics. Macedon itself actively and intensively cultivated its links with the rest of classical Greece, that alone tells you all you need to know.