I agree. The first post I understand, because it's suggesting that FAMs are security theater and of little practical benefit. Mr. Maclean is selling a solution (the mobile secondary cockpit barrier system) that can apparently be retrofitted. Whether or not that solution is of real practical value vs. the current FA + drink cart blocking method is being debated here.

The second post is just that air marshalls are tired and prone to drug/alcohol abuse, which could make them more of a danger and an active threat to pax (which is I guess why he excerpted about the part where an air marshall hallucinated and started firing at people that weren't actually there).

In related news (to secondary barriers...)

The house passed a bill that requires new planes to ship to US airlines with Secondary Barriers at the end of April. Of course, whether or not it passes in the senate with that language and whether or not the bill will be approved/vetoed by the president is a whole 'nother set of potential obstacles, and even if it did it wouldn't require secondary barrier installation on existing aircraft.

I personally see the retrofit and having to hook up some crazy barrier system consistently to multiple mount points that need to be added to an existing aircraft AND strong enough to survive both repeated use and an adult throwing their weight at it as impractical and of minimal benefit over the existing cart solution. I'm not really opposed to a requirement to put it in new aircraft because if the aircraft is designed with a secondary barrier option in mind it's going to be easier/quicker to deploy and likely much more robust than any retrofit solution.