Wow... your worldview is apparently informed by such bad misrepresentations of events that, what you end up describing, never actually happened.
NEVER Did Obama say 'meh who cares' about chemical weapons red lines.
He DID however respect that it requires congressional authority to launch an attack EVEN if he promised one - and when this was not forthcoming, abandoned his promised attack for crossing said red line.
Funny how, in the space of a single sentence you went from complaining Obama didn't seek enough authorization to declaring it wrong that he refused to start a war WITHOUT authorization.

Ironically, at the time of that attack - there was one extremely vocal member of the public repeatedly declaring that it would be utterly unconstitutional for the preside to launch an attack on Syria without authorization despite their chemical attack. That vocal member of the public was Donald Trump.

3 Years later he did the exact thing he told Obama would be 'unconstitutional'.