Your question is open to interpretation. Is walking up Snowdon suitable for young people? - depends which route(s) you take. Walking into Read's properly equipped, along with usual caving practices is fine; walking on/crawling between poised unstable boulders isn't. Read's is an active cave - it's constantly moving. It's up to the trip leader(s) to determine, via ongoing hazard assessment, the wisdom of the route ahead and its suitability for the group members - or, the suitability of the group members for the cave.