Centralized stuff is the relic of the past. It is safe to say we dont have this issue on the table. Security? This is a broad term. Its impossible to brutalize MASS chain, double spend the coins etc. but its still possible to attack the consensus by accruing huge amounts of coins. Scalability, I dont think in MASS case this concern should be of relevance. MASS cannot scale past 3 txs per sec and is overall a dodo joke coin. Do not bother about it.
What? Centralization is story of past, are you serious man? Centralization is the basic block on which whole building of crypto stands. MASS is not only about scalability, security and centralization. Just go through the section
what problems mass can solve? and you will know many things about MASS.