Yes, he is a horse, and especially if he's not used to it, it can be incredibly stressful for them to be cooped up in 'solitary confinement'. I would start by giving him a 'calmer' of some kind, such as a homeopathic, 'Rescue Remedy' or such. Then I'd gradually desensitise him to being in. Start out bringing him in for very short periods, a number of times over the day, until he's fine with that. Make sure there are as much 'goodies' associated with being in as possible, such as feed, grooming if he likes it, other friends to visit... and no further Bad Stuff. Eg. don't take him in there & tack him up for work.
As he's obviously quite upset about the idea at the moment, and you have gone into winter already, you may have left it a bit late this year. I'd consider that unless the horse is seriously lame, a muddy paddock is the better evil than a horse that's going to be in serious stress. Speaking, BTW, from an environment that's 'seedy & thrush central' due to being muddy half the year, and stables aren't that common, so I see unprepared horses 'condemned' to stables, and, more frequently, thrushy hooves in far from ideal environments, out in it 24/7 due to lack of any option... yes, it's not great, wish it could be avoided, but their feet don't tend to fall off either, especially if other methods to keep them (relatively) healthy are taken too. I think they are generally far better off than many who are stabled part/full time, especially when not accustomed/relaxed about it.
If it's a 'medical emergency' that he seriously needs 'stall rest', then he may need to be sedated.