Always better to have a convoluted workaround rather than get it right first time!
Especially when that workaround is as simple and fun as requiring the supporter to not only realise what has happened, but then pro-actively doing the legwork of identifying a 'non-ST but sold for Cambridge' seat or two that they want, and then somehow put in a 'save the seat' request to the ticket office (who would absolutely understand the situation) for the rest of the season, whilst simultaneously purchasing a different ST seat that they don't actually want, other than for Cambridge.
We'll have to agree to disagree. It may not be a big deal to those unaffected, but it's likely to impact the sale of half STs and, crucially, it is completely and utterly avoidable. Just like ST holders not getting first dibs on their seats for the FA Cup.
As an aside, it's always baffling as to why, when the club make an obvious and completely avoidable error, we always get those (completely unaffected, of course) rushing in to explain how it's actually all perfectly fine.