First, FireEye was one of the companies who worked to secure Equifax prior to the breach as mentioned by the CSO of Equifax on page 4 of this FireEye white paper from 2012 [1] that FireEye has since retracted [2][3].
Second, that is kind of a non-sequitur. I did not say that a nation-state did not pull off the attack, my gripe is that they are implying, like every other company that gets breached, that only a nation-state has the resources to pull off such an attack with their wording. These attacks are extremely cheap and easy, that is why we see governments running literally hundreds to thousands of such attacks/programs in parallel as evidenced by the CIA Vault 7 leaks. A single branch of the US government was literally developing hundreds of independent tools/programs that could successfully compromise anything they cared to target.
Third, define "easy". I define easy as ~$1,000,000-$10,000,000 since almost any moderately-sized corporation, of which there are millions, could fund such an operation. To put it in perspective, $10,000,000 is only ~1% of FireEye's revenue. I define "only a nation-state" at 1,000x more at ~$1,000,000,000-~$10,000,000,000 since although it is still technically doable for a large multinational or organized crime, it is unlikely to be profitable outside of theoretical large-scale extortion attacks.
Do you think a penetration test of 3 engineers working fulltime for a year would fail to materially breach FireEye's corporate systems? Almost every penetration test by a competent company takes a fraction of that effort even against well-funded security teams. And 3 engineers for one year is only 3 engineer-years which at $300k/engineer-year is ~$1,000,000, the bottom end of "easy" and 1,000x less than "only nation-states can pull it off". If engineer-years is too abstract, the Google ProjectZero case I mentioned earlier was a zero-click iOS RCE from zero starting understanding in 0.5 engineer-years. So, doing some sloppy extrapolation, is it easier to find 6 zero-click iOS RCEs or breach FireEye's corporate systems?
Let's say we moved up an order of magnitude to 1% of FireEye's revenue at $10,000,000 which is the high end of "easy" and is 2 orders of magnitude less than the bottom end of "only nation-states can pull it off". That would be enough to fund 30 engineers working fulltime for a year or 10 engineers working fulltime for 3 years. Do you think FireEye could prevent a material breach? I have literally never heard of a single person in enterprise security who has ever dared to make such a remark on the record that was not instantly taken down for a fraction of that. I know of no competent engineers in that space who would support making such a statement to anybody who could and would test it. Just think if FireEye announced a $10,000,000 prize at DefCon to breach their systems by the end of the year, do you think they would even last the month?
[1] http://www.cnmeonline.com/myresources/fireeye/fireeye-cso-le...
[2] https://web.archive.org/web/20120610031926/https://www.firee...
[3] https://www.fireeye.com/CSO_WP_LP.html