Note that you've focused on the parts of the article that downplay or would cast doubt on the Turkic link. When looking at the article from top to bottom, here's what's missing in your post:
The first part of the article, while sounding convincing about the trutfulness of the theory, doesn't bring any evidences by itself
.This is why I did not mention it.
While the language was extinct in Danubian Bulgaria (in favour of the Slavic Bulgarian language), it persisted in Volga Bulgaria, eventually giving rise to the modern Chuvash language.
Or the Volga Bulgarians could have began speaking it as well.
When you take the article as a whole, you leave with the situation where a majority of scholars conclude one thing, while a minority conclude another with some reasons given plus sources behind those positions. That's no accident.
Just because the majority of scholars accept it, it doesn't mean it's true.
By the way, why in the hell are we nitpicking over Bulgar?
Because I can't really stand this ridicolous theory anymore.
Britannica Online - The article describes the position of Bulgar and Chuvash in the classification of the Turkic languages.
Sergei Starostin's Tower of Babel - A Russian Turkologist's take on Danube Bulgar inscriptions and the Bulgar calendar, in Russian. The article contains a tentative decipherment of inscriptions based on the Turkic hypothesis.PDF (350 KiB)
Rashev, Rasho. 1992. On the origin of the Proto-Bulgarians. p. 23-33 in: Studia protobulgarica et mediaevalia europensia. In honour of Prof. V. Beshevliev, Veliko Tarnovo - A Bulgarian archeologist's proposal. The author concedes that the ruling elite of the Bulgars was Turkic-speaking as evidenced by the inscriptions etc., but stipulates that the bulk of the population was Iranian.
The first article only takes what is said to be true; the second one does make some attempts - now correct me if I'm wrong - as far as I know no turkic word begins with more than one consonant - is this so? Since I can definately see such one. And also this decipherement, as with others, hasn't gained wide acceptance. I couldn't be bothered to read much from the third article, which is essentially a wall of text, but as far as I understand based on archeological evidences it claims that the majority of population was of Iranian origin. However, the origin of Scythians and Sarmatians is whole another topic.