It was a Phillipines flight, the Bojinka plot. Ramsey Yusef, I think. It is not a good argument because that incident happened in 1992(?). Killed one dude, blew a little hole in the plane, but it landed safely. Not saying that the death of one is not a big deal, but apparently not big enough to enforce a liquid policy 15 years ago.
Different mindset now. Even the threat of something like that would send DHS and TSA into a tizzie. Common sense was used then.
Besides, it wasn't really a "liquid" explosive as it was stabilized with cotton balls. Liquid nitro never would have made it to the airport. ETD would have picked it up too.