I think the best options are letting her know all the potential outcomes and let her decides. She bears the whole accountability and responsibility for her own actions afterward.
Dang, your friend safety might be in danger if she actually went ahead and go to Bangladesh. He doesn't seems sincere with your friend at all, could be only doing it for some ulterior motive, mostly done so to get permanent residence for the country.
Guy is definitely sketchy, we can all agree. idk how close you are with this friend, and how safe is it to involve other friends and family but she needs to be removed from his temptation almost immediately (imo)
legal stuff:
marriage in thailand - that man is talking a fuckload of nonsense if the promise is somehow going to be a civil marriage simply because he's parroting a MUSLIM-MALAY tactic to "kahwin in Golok". There's even a cottage industry set up for it, but certainly if it happens she needs to be registered as a Muslim. Sure, let's say he somehow understands it will have to be a civil marriage going up north somewhere in Nara. Let's say she changed her mind or not even to that point, decides to go for it with no one she knows as strangers standing in for witnesses at the registrar. In a place whose main language I assume she (OR HE) doesn't speak. If you need someone to sit on her so she won't leave the country... I won't judge.
once back in Malaysia if she wants to keep the marriage legit, yes she'll need to register here. HOWEVER, because of his Muslim status (despite being a foreigner, which can provide some cover, if they know what they're doing), it will have to be registered as a Muslim marriage, she will have to legally convert. Think of the long-term impacts, even if you're not practicing. Once you have that status on your ID, there's a whole different world regarding family inheritance, alimony, child custody, and even death. He doesn't seem like he's interested in having a Muslim wife, and theoretically (almost certainly) he's going to hang her out to dry. Divorce in syariah courts is a dicey affair and is still very much biased for men. At every stage of this, she'll be a Muslim in the eyes of the law.
I believe civil marriages are still possible in Bangladesh but it is even more a Muslim-majority country than here, so while there is something called Special Marriages for interfaith, idk how easy is it to get that compared to a more typical registrar who's used to same-faith marriages. But if she resides in Malaysia, and intends to register her marriage, then you need to ask ppl who can advise on how to get around the Muslim status of the dude.
registering herself as a single mom... yes, you can put No Information under Father's detail. But if she's a Muslim on paper, she's liable to find that since being unwed is against syariah law, her baby will be taken and be put up for adoption. this is not a given but not unlikely anymore (esp if hospital staff feels morally called to be a busybody about this)
but let's say you don't want to come on to strong, because that might make her reluctant to share her situation with you... my ideal scenario then is that you and friends be on standby (with resources) so that at every point when she has cold feet, you can take her away.
Also insist on involving the guy's parents/family in Bangladesh, if your friend is actually going ahead with going back there. And make sure she's not alone in whichever country they've decided to get married in.
which reminds me, check with her state of finances. the guy might already have been asking her for money to help pay for stuff.
Your friend really threw all caution out of the window.... Has she always been like this? How's the family background (parents still together or divorced, how's her childhood)?
i think this dude is sketchy as hell, but let your friend be imo, better not interfere.
Personals, dating advice, have at it.