The phrase 'so as to' should mean that the offence will be complete whether the offender has intentionally or recklessly managed to get the light pointer on the aircraft.
I would imagine the basic points to prove would be that the offender was the person in possession of the pen, that they had shone it towards the aircraft and that the pilot had been 'distracted' in any way.
I will try to check on this later and post an update. Given the fact that for obvious reasons pilots struggle to pinpoint the location of where the light was shone from, it is difficult to catch offenders in the act.
What would be useful is for it to be an offence to be found in possession of a laser pen or similar implement in a public place. That way (in uk) if police have information of when and where (roughly) l@ser pens are being used, they will have good grounds to stop/search individuals in those areas, pro-actively looking for said items!
This would be similar to current going equipped to steal and offensive weapon legislation. In fact, possession of an offensive weapon legislation could be used to arrest someone found in possession of a pen now, (article adapted for use to cause injury) although im pretty sure thats not been tested in the Uk so far.
TBL