“The Case of E1b (E-V13):
To define the original Illyrian markers, we must also look at what they weren't. The E1b (specifically E-V13) lineage is a central part of the modern Balkan mosaic, but its story is different. E-V13 is of Neolithic origin, arriving with the first farmers from the Near East and North Africa.”

Ev13 is illyrian. We have a north illyrian sample of ev13, an upcoming one in slovakia, and ones of illyrian mercenaries from himara. it also came from anatolia, as its an anatolian farmer lineage, hence the name. not MENA. ev13 itself formed in the balkans too, it was its ancestor el618 which moved in the balkans in the neolithic to mesolithic (some studies like 2008 battelgia suggest, especially after later studies finding ev13 dated 7k bc in catalonia, which suggests they had enough time to move to that region in the neolithic bc they arrived to europe in the mesolithic)

“While E-V13 is often called a "Paleo-Balkan" marker, geneticists distinguish it from the Indo-European "original" markers. E-V13 likely existed in small pockets and only experienced a massive population explosion during the Late Bronze or Iron Age—well after the R1b, R1a, and I2 foundations were set. In this sense, while E-V13 became "Illyrianized" over time, it represents a different ancestral layer than the Steppe-derived R-lineages and the Paleolithic I2 core.”

Illyrians were never pure r1b. Illyrians are literally the mixture of the cetina culture (r1b and j2b l283, which you left out) and local farmers during the bronze age. the illyrian ethnogenesis formed after this mixture, meaning ev13 is not foreign. Once again i2 has nothing to do with this. That same study you quoted also considers albanians descendents of illyrians genetically, especially paternally, and linguistically. And a population explosion doesnt mean it was absent, it just bottlenecked, and that is assumed bc of the yamnayans coming in and ev13 being an elite haplo assimilating into them, and because of lack of samples.