Don't expect a tidy message here. The title, "Not This," sets up a poem that keeps refusing to be pinned down, and the two short stanzas read like attempts at definition that swerve into something odd. In the first, "warmer" is described as "sentences conjoined with / complacent gratuity," which sounds like language joined together without much effort or care. In the second, grammar, usually the rulebook for how words connect, becomes "the space between / carrots in a glass." That image is strange and a little funny: grammar isn't the carrots, it's the gaps around them.
The speaker doesn't sound angry or emotional so much as playful and detached, like someone testing how far a definition can stretch. The mood is dry, puzzling, and quietly amused. Judging by the phrasing, the poem seems more interested in how words behave and relate than in telling a story, so it's best read slowly, as a set of small pictures to puzzle over.