Here's some exact mathematical data for you:
I just measured the exact distance from the left hand side of my TV screen to the left hand side of Iron Citron's body and it is about 4 inches in his stationary state (when not taunting and/or moving).
The distance from the right hand side of his body to the right hand side of my TV screen is about 17 1/2 or 18 inches in Citron's stationary state (when not taunting and/or moving).
So that means that science and exact mathematics FAVOR players to take cover while being able to see on the right hand side of Citron's body, especially since his weapon fires from that location. This is NOT called "head glitching", it is NOT a "glitch" by any definition of the term, and it would only be considered cheap by people who don't understand what they're talking about... On the same token, people who consider the idea of taking cover to be "cheap" (in a third person shooting game) would probably rather a player on the opposing team simply stand in front of their shots instead...
Once again, we are dealing with FUNDAMENTAL third person shooter mechanics; nothing more. Does Garden Warfare have bugs and glitches? Absolutely. But what you're describing with Citron and Captain Canon isn't one of them...