Across the whole legal system, guilt has to be proven, if the prosecution can not prove guilt, then it didn't happen.
If Mr Richardson's evidence, the hundreds of tax payer funded hours of investigation and the ceasure of someone's personal diary was insufficient to obtain a conviction , perhaps there is a reason you that.
From what I've heard this individual was sacked by another operator prior to working for barrier, was universally hated by all at barrier and sacked for multiple dangerous acts in an aircraft.