Sounds like you had the reverse experience of what is usually the case. Like we have debated several times before, the vintage owners (normally) are the more passionate guys with a more expressed sense of fellowship. We have previously argued that the newer (98+) cars are often purchased by wealthy people that want a cool car but does not have any real Porsche passion.
Maybe this guy in the older car had had too many experiences with guys in newer cars not returning his wave - thinking they are all posh turds and snobs. He thought it was time for payback, not knowing he actually met up with one the most dedicated Porsche guys on the block - disguised in a 996..