Yes, of course is the Paris climate agreement not worth the paper it’s printed on and one could argue the USA is the only and last honest country in the world. Yes, maybe. But still, it doesn’t cast a sympathetic light on the US for placing themselves outside (and above?) even the most inconsequential international agreements … for petty reasons.
AFAIK are Trump’s reasons for not signing more or less of personal nature (he hates China) and even more silly than the agreement itself.