DEI is a dog whistle in that for conservatives it means woke. They want companies to continue oppressing non white, non-cis, non-hetero people. Or at the very least, not actively elevate them.
Oh, for sure. I agree with you that this is not dogwhistling; I was just quibbling a little over your description of what dogwhistling is. MAGAs use a wide variety of dishonest rhetorical tactics: there's lying for the purpose of outright deception, dogwhistling to signal intent while maintaining deniability, and then whatever this tactic is called -- euphemizing, maybe? -- to state their idea plainly but spin it as less bad than it actually is.
Ah, fair, yeah coded language was what I was getting at rather than lying, but you've put it better. Honestly, I think this is just saying the quiet part out loud, they don't seem to care any more.
No. It means implying something from something more tame. For example, in this case, it's an objection to any support for gay, trans etc. Rather than saying that outright, they'd say DEI is over the top. Which is attending to sound subtle and against a policy or practice when it's against minorities. Its a dog whistle. Like anti-immigration is usually used in as a racist dog whistle.
It needs to have a coded element to it, some people hear what's really being said, some do not, like an actual dog whistle. There is no coded element here, it's explicitly attacking gay, trans, women, basically any minority group because that's expressly what DEI is about.