"Recent" is the key word, here. The PT event was 250 million years ago, and the Earth was a very different place then, including being significantly warmer.
The Holocene climatic optimum, on the other hand, was something like ten thousand years ago, and it explored temperatures that we're not close to (yet). If there were a life-ending loaded clathrate gun out there, the Earth would have hit it and triggered it then, not when we're experiencing relatively cooler temperatures now or in the near future. Unless it somehow got loaded in the ten thousand years since then, but no one thinks that.
ETA: To be clear, I'm not saying that climate change is fake, or that it's harmless because temperatures have been higher in the past. Those are orthogonal arguments to this (and they're bad arguments). This is just a statement about whether we're going to accidentally shock the globe into a radically different climate by triggering a methane clathrate gun.
The Holocene climatic optimum, on the other hand, was something like ten thousand years ago, and it explored temperatures that we're not close to (yet). If there were a life-ending loaded clathrate gun out there, the Earth would have hit it and triggered it then, not when we're experiencing relatively cooler temperatures now or in the near future. Unless it somehow got loaded in the ten thousand years since then, but no one thinks that.
ETA: To be clear, I'm not saying that climate change is fake, or that it's harmless because temperatures have been higher in the past. Those are orthogonal arguments to this (and they're bad arguments). This is just a statement about whether we're going to accidentally shock the globe into a radically different climate by triggering a methane clathrate gun.