OK - I guess they're trying to avoid touts being ST holders, which is not an unreasonable thing to want to do, given how popular OT tix will be to (particularly) occasional visitors to the UK. As you say though, near impossible to police. Would appear that this guy has been rather unfortunate...
“If an away match ticket is transferred or found in the possession of another supporter, the club will discontinue your ability to apply for away games."
“If a ticket is resold to another supporter your season ticket will be cancelled without refund, and you will be banned from buying tickets...