After attempting suicide at the end, it turns out the gas pipe he tried to turn on didn't work. So Tom opted to run off yet again, but changed his name to Felix to cut ties with his past with Kitty White and her litter.
The shorts almost serve as a middle ground between the silent era Felix (as several of the surreal gags of the old cartoons are still present in the VB shorts) and the Trans Lux Felix (which took the animated cartoons in a much lighter and softer direction).
- Semi-confirmed in an episode of The Twisted Tales of Felix the Cat (which reuses elements from the Joe Oriolo cartoons); in "The Underwater Kingdom", the Van Beuren era Felix cartoon Neptune Nonsense is seen on TV and is what kicks off the plot of the episode, and Felix instantly recognizes the cartoon on seeing it.
Which would explain his inconsistent characterization, childish personality and foolish stubbornness; his mind and memories are simply getting scrambled from old age in spite of his genius level intellect.
Well that would explain why he looks different than the messmer felix, and the change in personality.