I genuinely couldn't see any lower league club putting in a legal challenge anyway.
All but 1 would have been worse off. As I've said previously they've all prepared squads to mount a charge on Championship 1 promotion. Built around a budget for those needs. Their aim is to win promotion with that squad and be in the Championship in 2018. If they were thrown in there now, they would be 99% guaranteed to be in Championship 1 in 2018 due to inevitable relegation after getting whipped every week. So while it may bring them some better gates this year, it means that long term, they are in a worse place.
The only exception is Toronto. I'm sure they'd love to be in the Championship this season with their squad. However the month's notice they'd have to do it in creates a total logistical nightmare because of their location. Because of them arranging travel and accomodation for both themselves and visiting clubs. Because of making sure their fixture lists are "4 home, 4 away". It just couldn't all be rearranged easily on such short notice.
So why would any team have an argument that they would have been better off in the Championship this year at a month's notice? Quite clear none of them would.