Indeed.

1. The form has been faxed in March of 2012 judging by the text on top.

2. According to his linkedin profile he was going to a business school in 2012 and 2013.

3. His article states that he has taken OPT to work for a year after graduation and at the end he got job offer at MuleSoft, which was in 2014.

So what was his work authorization in or before March 2012? It could not be OPT since he just started his degree in 2012 and OPT requires a year of study ( https://www.uscis.gov/opt ). He does not seem to have any work authorization other than OPT in 2014, when he has taken the job in MuleSoft so he has not started his GC application at the time (otherwise he'd had an EAD and would not need to go to Argentina for a year to get an L1 visa in the first place). So, given only the information from Linkedin I cannot see how he could possibly be authorized to work at the time. The fact he has not filled I-9 correctly just corroborates this.

I don't know the current situation, 30 years ago there was a period where my wife was working on her foreign passport + a letter from immigration. (Which was a total joke as the letter had no anti-tamper measures whatsoever, nor was any verification done against their data. I do not recall the state of technology back then to know how high end a setup you would need to forge it--with modern tech I could easily forge it with the stuff within 3' of me as I write this.)