The justification for textualism is that it's better to be wrong in a precise way, than to try to be right in a fuzzy way. But both models are wrong. Bit rot is real and applies to laws. It's not possible to keep laws up to date with what they would be if lawmakers had infinite resources to dedicate to lawmaking and maintenance, even ignoring the huge issue of democratic consensus and parliamentary procedure issues.

(All models are wrong! Some useful!)

The law is a tool which imperfectly models the goals of the lawmakers.

For lawyers judges, the beauty of law is that the law has plenty of room to support contradictory interpretations.