[Closed] 2016 bike for my Dad

So my Dad had an old 1997 GT Arrowhead which he's been using over the years as an occasional mountain bike/ shop bike / canal towpath bike. It was basically perfect for him - lightweight, no suspension, reliable, not too expensive-looking but at the same time quite cool. I loved it and was looking forward to inheriting it for doing wheelies and nipping to the shops on.

Anyway it was written off in an accident, so we need a replacement. ~£500 to spend, and he wants recommendations. He wants to use the local GT stockists but happy to take advice from wherever. He's 60 and was always a bit of a clumsy with no real intentions to do massive miles - so I think a drop bar bike is probably out of the question.

My own preference would be something like a GT grade, they now do a basic flat bar version for about that price. I suspect this would be a bit jittery compared to an MTB with 2.1 tyres. All of the mountain bikes around that price point look a bit uninspiring to me though - heavy with pointless suspension forks. 19 years of no progress add far as I can tell. Similarly, I can't get excited about hybrids, although they're probably the best compromise. I think I want a rigid mountain bike, but they don't seem to exist any more. Any suggestions?