Firstly, it is often mentioned that Thailand has large foreign currency reserves and that there are large amounts of "hot" money coming in, OK, probably true ... but this is ambiguous as for one we never seem to get to know from where it is coming from and what Thailand does with said foreign reserves. Let me have a guess, it's mostly Chinese money and it's being laundered in the property market (with Bangkok and Beijing looking the other way) so they have large reserves of Yuan which conveniently fits in with the junta wanting to buy all things Chinese (like subs/tanks/infrastructure projects etc.). This will obviously make the Baht appear Teflon in nature.
Secondly, the Bank of Thailand is scared of being labelled a currency manipulator by the US and seems they only just escaped it last time round, which I'm still trying to make sense of what the US actually thinks it should be worth as most folks think it is over valued ... unless they are going to be accused of manipulating it to making it too valuable, which would be weird.
Thirdly, the Bank of Thailand may want to lower the Baht but it has been suggested that the bank governor is just following his orders so that a select few can gain foreign assets and enrich themselves and when it it is allowed to fall again they can cash in again when repatriating it. Jury still out on that but it's happened before although the Baht wasn't a free floating currency then as it is now.
It seems like there is some skulduggery going on as most currency experts/economists don't believe it's a natural situation. Currencies like the Euro and Pound are doing badly because of uncertainty, not because of bad economies and markets hate uncertainty. Once the UK has decided on it's course, there is a deal or no deal/WTO and the path of the EU can be seen for the next 5 years then these two currencies should bounce back ... at least somewhat.
We'll see.

Edit - Typos