Fake or not, this scenario can happen in reality. And what the "troll" described corresponds for 100% with what could happen in reality. There was a problem and IB witheld 100K. The 100K are real actual numbers that can correspond with reality (should be 30%). The fact that IB took that money is logical too as IB would be held responsible by the IRS if the tax form from the accountholder was such that he would be taxable by the IRS. If the accountholder would escape the taxation, IB would have to pay and get on top of that a fine. The account holder refreshed his tax form. That is what has to happen if you have the mentioned problem. So that is like in reality. IB gave the money back. That's what happens normally in reality too.
eTrade did that to me once, they took 24% of the trade proceeds because some paperwork were missing. I submitted everything and then no news, so thought all was good. Then on Dec 31st, got an email at 11pm asking me for more paperwork before an end of year deadline. I only read the message 1 day after, and then submitted the missing paperwork on Jan 2 when markets were opened again, thinking all was good. Nothing. They took something like 800 USD. I call their support and their reply was "too late, everything was sent to the IRS on January 1st at 00:00am and I needed to call the IRS instead" to get it back. This was for an offshore corporation. I tried to call the IRS corporate line, waiting time: 3 hours my time is too precious for that shit, took the 800 USD loss as a life lesson
since you had an offshore corporation you must have had an accountant doing your taxes. So it would have taken them like 5 minutes for you to get the money back as part of your tax filing
it was not a tax issue, it was a reporting issue, they wanted some kind of silly disclosure signed. The document was easy to get, the problem was the timing, Dec 31st email at 11pm ET for a 12am deadline it was impossible to get on such short notice, and I was not to pay tax anyhow for capital gains. Just some silly compliant officer fucking up his daily job
They did apologize for the fuckup still not worth it the IRS hotline is impossible to get through for corporations.