I am a little bit confused. I believe Saul Alvarez is being regarded as a current 3-weight world champion. Without a doubt, he is a legitimate belt holder in 2 divisions (great achievement, though I believe he was incredibly fortunate to get the nod over Gennady Golovkin). Since when was the WBA (regular) belt regarded as a legitimate world title? I have also heard people refer to Lucas Browne and more so, Alexander Povetkin, as former world champions. They only held what Manuel Charr has now, and who the hell regards him as holding a portion of the title? The WBA (regular) is akin to these interim, "international", "silver" titles other governing bodies dish out. There are too many belts being banded around as is, without this nonsense.
Canelo is a 3 weight world champion 154, 160, 175 Regular doesn't count but if it did he would be a 4 weight world champ
It depends who you talk too. I personally do not consider him a SMW champ. From what I've seen many GGG fanatics consider that version of the title as a legitimate world title.
He's being regarded as a current three weight world champion, with those referring to the WBA (regular) as one of the three titles.