That is true for UKAHFT but it isn't true for FT.
For any BFTA events in the UK and for the World Championships ( WFTF ) JW's / SR's etc are classed as Piston rifles and compete in the Springer/Piston category.
The T16 would be legal to use in both the BFTA Grand Prix series and the WFTF World Championships in FT - competing in Spring/Piston category.