I think post-ironists mostly conceive of irony as winking insincerity. What they are reacting is more like facile ironic posturing rather than irony per se.
The definition might be too broad. Take euphemisms for example, it seems there is a subversion between the intention/action (?) and the expression or literal meaning. Imagine a politician saying “peacekeeping efforts” to talk about military interventions.
But I wouldn’t say euphemisms are ironic.
I’d say euphemisms are frequently ironic. Think of The Rolling Stones repurposing the phrase “mother’s little helper” as a euphemism for drugs taken by a mother. I think that’s pretty clearly ironic, & even when the irony isn’t intentional, I think there’s generally an irony inherent in trying to give something disturbing or distasteful a more innocuous sounding name.
Euphemism creates a gap and a tension between expression & meaning that is inherently susceptible to ironic interpretation. Your own example of peacekeeping is a perfect example of a euphemism that is vulnerable to ironic interpretation.
Irony need not be intentional. It just requires that there be an intention and that the intention is undermined by the action, expression of that intention. If the audience perceives the euphemism as patronizing, deceptive, manipulative, or hypocritical, rather than acting as a social lubricant, the euphemism becomes a point of increased friction. An ironic reversal of intent.
Great Writers like Kazuo Ishiguro and Bret Easton Ellis and filmmakers like Kubrick, Lynch, or Solondz deftly expose irony in situations where irony is not apparent and that irony is often only perceived as uneasy tension by the reader/viewer. I think the potential for ironic interpretation abounds in the human experience.
I would say that word play is inherently somewhat ironic in that such meaning as it achieves is achieved by subverting meaning. Although substituting word for another word that rhymes with it is mostly ironic because it is an attempt to be clever by being silly.
What about rhetorical questions?
I would argue that rhetorical questions are basically a form of Socratic Irony. They are ironic in that they reverse the purpose of questioning. Rather than seeking knowledge, the rhetorical questioner is imparting knowledge by modeling what they think ought to have been the interlocutor’s internal thought process before they spoke or acted.