Am I right about the "under 24" requirement?
I guess the only reason IRS has not caught him yet was the massive Covid upheaval
Yes, you appear to possess a very informed view regarding the "HOH" deduction and it's application.
The IRS does a very thorough job of vetting taxpayer returns.
That said, here's a better answer to your assertion:
More than 21 million paper tax returns are still waiting for processing by the Internal Revenue Service, as the tax agency struggles to swiftly disburse refunds to American households, according to a watchdog report released Wednesday, 22 June 2022.
Most taxpayers file their returns electronically, but millions of others — disproportionately the elderly — still fill out their returns manually. National Taxpayer Advocate Erin Collins said in her report that the IRS backlog this year is 21.3 million paper returns, 7 percent more than the 20 million that were awaiting processing at the same time last year.
The report may add to the political headaches for the IRS, with Commissioner Charles Rettig's term set to expire at the end of this fall. The agency has faced budget cuts, outdated technological systems and a depleted workforce that have made it less responsive to taxpayer needs. But the growth of the backlog of paper returns relative to last year amounts to a setback for the agency, after Rettig vowed to "crush" the backlog this year.
The Internal Revenue Service closed the most recent filing season with more than 35 million in unprocessed tax returns, as the agency's backlog grew markedly amid a crush of challenges related to the pandemic and economic relief efforts, a government watchdog said Wednesday.
Erin Collins, the National Taxpayer Advocate, said in her report that about 17 million paper tax returns are still waiting to be processed and approximately 16 million additional returns have been placed on hold because they require further review manually. Another 2.7 million amended tax returns have not been processed.
This backlog represents a fourfold increase from 2019 — the most recent year before the coronavirus pandemic — when the IRS closed its filing season with 7.4 million unprocessed returns, according to the report. These numbers reflect the IRS backlog as of May, and the agency may have made progress reducing it since then. The IRS backlog amounted to 11 million at the end of the 2020 filing season, fewer than a third of the current number of unprocessed returns.
In actuality, the IRS has a daunting job.
The IRS does the best it can using 1980s designed, mainframe COBOL programs.
Tax Cheats Stiff Uncle Sam by $381 Billion Per Year, IRS Study Says
...
https://www.washingtonpost.com/us-policy/2022/06/22/irs-refunds-taxpayers-returns/
...
https://www.washingtonpost.com/us-policy/2021/06/30/irs-backlog-returns-taxpayers/
...