Because Ernie looks just like Otto Octavius, aka Doctor Octopus...
And Doc Ock once tried to steal Captain America's shield so he could use the vibranium in his mechanical arms. Doc Ock was always looking for an upgrade, and so was Ernie, who made the greatest trade in Giants history.
Doc Ock also paid a bunch of bikers to distract Cap so he could steal his shield, and we all know that bikers love tattoos...just like Colin Kaepernick.
It just makes too much sense not to happen.