I hate assuming, but I wouldn't be surprised if there was some discontent on Galvis' behalf. He's always been an starter who plays everyday. The Jays could have picked up his $5M option in the offseason and tried to deal him - but in reality, he isn't worth anything anymore because his defense is just good now (instead of great, which it was in 2016 and 2017). Iglesias is superior to Galvis and he was DFA'd this past offseason and had to accept a minor league invite IIRC.
Will be curious to see if more comes out on this story. Maybe some stuff happening behind closed doors - maybe just the Jays doing him a solid so he can catch on and play more on another team. He's only a great guy to have on your bench if he accepts and embraces that role. If he's pissed off, wanting to start than he can become a distraction.