Jam, Aussie and NZ Tigers have fuel drains installed at the rear of the tank following an accident in NZ caused by water entering a tank overnight whilst parked in rain. Mandatory AD. Anyway it's maybe not a factor in this accident.
Re the accident pic: A good landing attitude apart from the low wing. I can't imagine getting in to that position on t/off. The go is to get the tail up early. If the field is soft/wet then maybe a bit tail low. You get a feel for it after a bit of practice. As has been said, if the aircraft is not accelerating then try something else or give it away.
To be honest I've never attempted a three point takeoff in a Tiger, but I know of other tail wheel aircraft that have come to grief attempting it, but not deliberately.
Maybe tail wheel aircraft can lift off in ground effect lower than the stall speed in a three point attitude, but that's never going to end well unless the aircraft is very over powered - not the case with the tiger.
Any Aerodynamic experts out there?