All common stock shareholders got zero.
I assume you mean the stock was cancelled (by the company), so you didn't receive any payment and cannot receive any in the future. If you still have any legal right to possibly receive something, it means you haven't yet definitely lost everything, at least for tax purposes.
Should I expect any tax documents from ...
The capital loss can be carried-over as many years as the investor lives. So the capital loss is an asset. But the capital loss only offsets $3000 per year in income but will offset any amount of capital gains up to the amount of the capital loss.
Now say that the investor, who has a carryover capital loss, is making 1.5% annually in three-month Treasury ...
Yes, that's perfectly legit. Capital losses are anti-income, and are tax deductible in principle... But there are some artificial limits, and the accountant is advising how to avoid those. Nice thing, this deductibility bypasses the annoying $12,000 standard deduction, so you can deduct even if you don't itemize.
Capital losses can offset capital gains
You can only offset $3,000 of ordinary income with capital losses for the year (unless you're a full-time trader). The accountant's advice is that they should shift money to a brokerage account to generate capital gains which can be offset entirely by the carried over losses.
As Dave points out, it is good tax advice, but might not be practical in their ...
The annual capital loss deduction is $3,000. In order to utilize a larger loss you must:
Harvest capital gains that can then be offset
Be a full time trader (in size and volume) who has been granted Trader Tax Status by the IRS (hardly the type of person that would be looking to Dave R for advice).
You can carry losses forward indefinitely. Or, at least, until they change the tax law again:
The 20-year carryforward period has been replaced with an indefinite carryforward period