They actually had the right idea in one respect with the MDF. As Jonathan mentioned, they chose it for its flame resistant properties; it is hard to set on fire, just tends to smoulder and blacken.

But yeah the attachment method didn't seem the strongest; that's the same with anything though. Having 20mm Hardox armour is great but if it's only held on by two M4 bolts, then it ain't much use
Though considering it was their first robot and built in five days, they had a hell of a go. Really nice to see a low-budget machine; hopefully they have the bug now and we see them again, and hopefully they've inspired other have-a-go builders working from sheds who don't have access or tools to work with the fancier materials.