It could also be argued that the INTER/TEMPO holding fuel requirements are only intended to cater for inaccuracies in the weather forecast. They provide some protection in case the weather is worse than forecast and ends up below landing minima, preventing the aircraft from landing. In that light, the enroute holding has no bearing on the destination holding requirement. The INTER/TEMPO holding fuel should therefore be available until the aircraft is close to the destination and likely to land within the 30/60 minute period.
Some interesting reading:
https://www.atsb.gov.au/media/32921/b20040246.pdf