As you ask..........
Some clubs with routed tracks allow sponge tyres, some don't.
That's true today and has been true ever since the 1960s.
For many years almost everywhere that runs sponge tyres have insisted they are dry when put on the track, but that typically wasn't the requirement back in the 60s.
Presumably this club isn't considering joining the ranks of clubs that allow sponge tyres.