Originally Posted by Often1

It was, in fact, TG's responsibility as the late-delivering carrier to reroute you to IAD. Your sole recourse is against TG and short of suing in a Thai or French court, you are unlikely to find any relief.

I would send a note to TG noting that you were delayed on arrival and misconnected as a result of a delay caused by TG, that you asked TG to rebook you (provide the name, description and location of the individual with whom you spoke), and that he refused to rebook. Accordingly, ask that TG reimburse the cost of the replacement ticket you purchased from UA. Keep it to that. It will almost certainly be denied. With that denial, make a claim against your travel insurance.
.