Oh, please. I still have fresh memories of well established banks (think, too big to fail) that required IE to view their sites. The fact that they do not support Firefox on Linux isn't much of an indicator of anything funny going behind the scenes.
You should see my bank's website. It doesn't let me use passwords longer than eight characters. Or symbols.
Chromium 41.0.2272.76 on Debian unstable does that too. Well it does not crash per-se, it just eats up all system resources and hangs ("Page(s) unresponsive" dialog does show, but is also unresponsive)
I tried it 3 times and every time it does that. Latest Firefox on Linux Mint.
I will not put my money there.