accident-prone apes...
a few years back i remember watching two baby chimps at taronga chase eachother to the highest branches of their dead trees and then scurry along a rope strung between them. it was very high up and the ground below that particular section is sydney sandstone. one grabbed hold of the other and two hung there, playfighting and suspended by nothing but one hand of one of the baby chimps, he didn't seem the slightest bit worried, nor did any of the adults despite the fact that they stayed like this for over a minute, frantically shaking eachother and playing in a way that appeared, at least to us humans, totally careless.
of course that little chimp hand held firm. and the two eventually chased eachother back down unharmed.
in the end however, i think apes, despite being so spectacularly more agile and co-ordinated than us, still make the rare mistake and sometimes this can prove fatal. i don't think there is much use being over-cautious. the benefits of ropes and tall trees/frames for apes, even small infants, greatly outweighs the risk of a rare accidental death.
of course its wise to minimise the risks as much as possible.
for example its probably not such a great idea to build your climbing frames over say, a tiger exhibit.
However, as the group hopefully grows larger, the young ones may use it a bit more often.