The way I see it, perhaps wrongly, is that a match is either senior or it isn't. The governing body determine it to be a senior match. That's clearly stated in the link I gave and used as a reason to prevent a player playing for 3 clubs in one season - as playing in a Premier League 2 match...
https://www.wba.co.uk/news/2017/january/wrights-yeovil-loan-cancelled/ - I'd agree that morally (wrong word but can't think of the right one) it's nonsense but if the Football League consider it a first team game, thus preventing a player transfer, I think technically it has to count as a senior...