Well, taking numbers is traditionally what train and plane spotters do, so there is at least a vague connection, and any sort of vague connection is suitable fodder for good old journalese, otherwise known as lazy/crap writing. Personally, where crap journalism is concerned, I'm awaiting the onomastic traumas Daily Mail sports sub editors will experience when a British Tennis hopeful crops up with a name that begins with a Z or a Y or some other unusual consonant, meaning they won't be able to alliterate the name with that little grass hill at Wimbedon that all those sad middle England mums sit on whilst they cheer on the latest sub-par Brit grass court player. I can see the scene in those newsrooms now as they sweat over InDesign with the deadline ticking nearer... 'I've got it, what about Polanski Promontary?'
Of course the difference between photographing choo choo trains and jimbo the jet plane, and scribbling down their numbers in a notebook, as opposed to noting down the numbers and times of vehicles entering a military base, is that most airports have a spectator area, and most railway stations have signs up which actually say that photography is allowed, but recommend that you let the station staff know that you are doing it. And since both aeroplanes and trains run to scheduled times, and there are books about with all those fleets listed, there's really no harm in noting such info, whereas noting the arrival schedules of military vehicles is the kind of thing partisans who are planning a mortar attack tend to do. Thus if you try that at the entrance to Stirling Lines, it should come as no surprise that some squaddy will likely point his L-85 at you and either tell you to 'piss off' if you are lucky, or more likely cock the thing and yell 'get on the ground NOW!'.
If it can be shown in a believable way that the guy really was unaware that such a thing was likely to be the result of what he was doing, then a jury really will believe he is retarded, so his defence pretty much hinges on his brief proving that he is a moron. And let's face it, the average person thinks train spotters are morons, so you can kind of understand the defence lawyer wanting the press to go with that label, and he or she may in fact have encouraged the use of the term with the court reporters in exchange for a press release. And that's another thing lazy journos and subs love - press releases - since all they tend to do is simply paraphrase them a little, and occasionally even type them in verbatim.
Al