Villavar Theory 

I strongly suspect the reliability of the citation provided. It is a book titled "History of Kerala" written by R. Leela Devi and published by Vidyarthi Publications. Vidyarthi Publications is primarily a publishing house of school guides. So I think it does not fit for Wikipedia:Reliable sources Even if we take the book into account, it says only this:

 

No reference given to the above statement in the book, nor it says who are these "some". Hence we are forced to consider it as either Original Research or weasel words.

I will be tempted to delete the above sentence along with all other mentions of Villavar from the article , if someone could not come up with a reliable reference to support  the connection between Ezhavas and Villavar (or at least claims of it).