I think you're overestimating the importance of politics and underestimating the prevalence of people wanting to make a quick buck.
An active warzone like Myanmar is not a good choice when you're a dissident looking for safety, but quite convenient when you're running a highly profitable criminal enterprise and can get an armed gang to give you protection for a cut.
Now, many of the 54,000 that quanfan is claimed to have returned from Myanmar likely weren't there entirely voluntarily (recruiters promise people high wages and generously charter a bus to get them to their new workplace; failing to mention that it's going to be a cross-border trip, they won't be allowed to leave until they've "paid back their debts", and room and board aren't free) and others are only providing ancillary services to the gangs (shops, restaurants, bars...) and didn't commit any crimes beyond crossing the border illegally, but from what I've read about people who were enslaved in Myanmar and managed to escape (e.g. https://mp.weixin.qq.com/s/rA9JHSPQJWjnjgaqC-B76g ) the drain caused by quanfan led to personnel shortages for the gangs, making it easier to get away.