Yes Thai Government did indeed fight it hard as it involved the...

Yes Thai Government did indeed fight it hard as it involved the public sector infrastructure asset.  They have passed cabinet resolutions to limit their future exposure https://hsfnotes.com/arbitration/2015/11/25/thai-government-lifts-total-ban-on-arbitration-clauses-in-state-contracts/

However, the Thai government has also acknowledged the change of global business trends and is promoting dispute resolution by arbitration to attract foreign investments - http://www.conventuslaw.com/report/enforcement-of-foreign-arbitral-awards-in-thailand/.  

Thailand has also enacted the Convention Establishing the Multilateral Investment Guarantee Agency (MIGA).

The enforcement of a foreign arbitral award under the Thai ArbitrationAct 2002 is identical to that utilised for the enforcement of domesticarbitration awards. However, to enforce a foreign arbitral award underthe Geneva Convention 1927 and the New York Convention on theRecognition and Enforcement of Foreign Arbitral Awards 1958, theaward must also satisfy the requirements of those Conventions.

The Thai Government will not be able to appeal or challenge an award or order unless (a) the recognition or enforcement of the award would be contraryto public policy or good morals;(b) the order or judgment is contrary to the provisions of lawgoverning public policy or good morals;(c) the order or judgment is not in accordance with the arbitralaward etc