There were clearly mental health issues involved here, no one of completely sound mind behaves in this fashion.
However, if you really want to end it all, there are ways to do so without causing chaos.
He was up there at 05:30, just around start of service, and apart from being spotted by the Heaton Norris signalman (apparently) there was no one else around, so there's opportunity to jump before anyone else gets there, *if* that's really your intention.
It seems that wasn't the intention here, but instead he wanted to cause disruption, or simply to get attention. He succeeded in both of those.
Trains were being run past, at caution, on both Down lines, he was therefore in full view of passengers, somebody had presumably decided that he wasn't going to take a dive in front of those passengers, or jump in front of a train, otherwise, surely, no services would have run at all, on any line.
Other options: attempt to persuade him to get down for an hour or two, after that, if the assessment is that he isn't an immediate danger to himself, withdraw the majority of the personnel, leave just enough to monitor, and reopen the lines, except the one immediately adjacent, then pass trains at caution, and wait for the person to decide to come down of their own accord. With any attention-seeking tendency unfulfilled, this may well have happened considerably earlier than 22hrs in.
Yesterday the weather was fine, I suspect this incident would not have lasted nearly as long if it had been cold, windy and wet.