It will be interesting to see how actively they enforce this new ruling. Given that paedo-tourists are effectively given a free pass in Thailand I find it odd that Bitcoin would work it's way to the top of the agenda.
I don't think the political will exists, in either case - the political jockeying that currently stands in for the entire totality of both policy and political discourse doesn't leave much space for a quiet and novel campaign like this - I suspect, in fact, that the only thing that has fallen into the above category within the last ten years are CITES violations (drug stings should probably be credited to the DEA.)
Normally, everything not expressely illegal should be allowed - and not the other way around.
Really necessary to drag that in to the discussion?
There is also some misunderstanding about who declared bitcoin illegal. The Central Bank deals specifically with monetary transactions - and they were asked for their opinion by a private company, and they gave that company their opinion.
That is the extent of what happened. The government of Thailand is not on a crusade against bitcoin.
edit: why the downvote? It's a simple question!
To use a real example I recently saw: "Russ Feingold said the Patriot Act violates the 4th amendment, voted against it, and says we should repeal it; however, Feingold sponsored the McCain-Feingold act -- parts of which were found to have violated the first amendment -- so his argument against the Patriot Act is invalid because he and other liberals also violate the constitution". This is an example of not only an ad-hominem, but also false equivalence, and to-quoque -- but yet I see these arguments commonly asserted and unchallenged.
For the record I do think the grand-parent comment does not constitute a particularly strong argument to me: there's no proof that Thailand fails to punish paedophiles any more than any other country (keep in mind these kind of crimes are grossly under-reported) and even if that is indeed the case, there's no proof that the same dynamic would mean laws against bitcoin would not be enforced.
This is not to say that the story makes Thailand look good. The ruling elite have a strong tendency to blame many things on foreigners, and since coming out against Bitcoin will effect practically no one in Thailand (which is not exactly a hotbed of Bitcoin usage) they get to blame another imagined foreign threat to the Kingdom and take credit for saving the country. Remember, they made a similar stance against, Open Source Software, not long after the military coup not that many years ago (and like Obama in Egypt, the Bush administration illegally continued to give them military aide without anyone in America even noticing).