Oh! Tornado winds are certainly likely to have some effect! He's probably generally nervous then, so it won't take much of anything else to make him downright frightened. As he doesn't trust you, I'd be careful not to be that 'final straw' and just quietly fluff around him until he begins to relax, as it sounds like you're doing. I'd take it at his pace for now, whatever that may be. Sounds like you're on the right track & will start to see some improvement with him soon.
I do agree with using treats as reinforcement, and if it's a once in a blue moon thing, lollies aren't likely to hurt at all, but if you're in the practice of regular treats, I'd be looking for a healthy, sugar free treat - I usually use the pelleted nutritional supp that my horses get anyway.
Yeah, it doesn't matter that you haven't yelled at a horse in a week, but that this happened before he got to know you & gained trust in you, and first or early impressions tend to count a lot higher, as there's nothing else to put it into perspective. Also animals don't tend to understand punishment too well anyway, and especially horses being prey animals, tend to get worried about aggressive behaviour by us predators.
Punishment & 'shock tactics' can indeed be handy sometimes, IMO, but you need to understand the principles behind it's use and the 'side effects' to know when it may be a good idea & when it's best avoided. Eg. it is also generally a temporary 'fix', so I'd also be working out why the pony is kicking & what you can do change her attitude before the behaviour resurfaces...
And back to your original 'dilemmas' that I didn't answer... No, I wouldn't send Shrug away, as horses are herd animals & tend to feel more secure - not to mention happier - in company of other horses. You may consider separating them when you want to give the little guy your attention tho. Perhaps have him in a yard without her when you're sitting with him, so you can be the sole focus.
Will anyone buy them untrained? Yes, all horses start out this way!
Does depend how old they are as to whether someone might think it worth starting them, but there are plenty out there(me included) who would prefer to buy unhandled animals. I don't like buying 'broken' horses because I don't want to have to fix them!
Yes, telling the truth is the best idea, not only for decency & the sake of the buyers, but for the little guys in question. If they are untrained & you decide to keep them, I would definitely be finding a competent and *considerate* trainer to help you with them. Especially if it's your young kids you're entrusting them with.
On the question of trust & possible abuse, yes, horses are very forgiving, and so long as you prove to them you're trustworthy(be aware of your bodylanguage - horses are but people often aren't, so 'say the wrong things' even without realising), they'll come around. Of course, frightening them with yelling wouldn't have got your relationship off to a good start
, and their previous experiences obviously haven't either, so it may take a bit of time & patience to get over those hurdles. Horses are so adaptive, but they are still prey animals, evolved to be reactive, especially in the face of anything unfamiliar, so I wouldn't take it that they were necessarily abused at their original home. It may be that they just weren't desensitised to a lot of stuff, environments, etc.
Regarding your comment about man v's woman, no, it's not silly at all. Horses don't generalise well & are perceptive to the smallest differences. Horses are also frequently known to have a problem with a certain sex because of bad experiences(or men with beards, women with red hair, Men With Tools(bad farrier), etc, etc). Eg. after I had my kids & no time, I decided I needed the help of another trainer for my green horse.... & unfortunately chose badly. My previously friendly with everyone, trusting horse even years later still is very wary of anyone he hasn't learned to trust & downright frightened of men! Except my husband who he's got to know well now. But back to horses being forgiving & adaptable, just start wherever they're at & work gradually, easily, considerately from there & they will quickly learn that you're OK.
One other consideration; how big is the pony(you said she's 2yo), how old & big is the mini & how big are your kids? It's also very possible their behaviour is related to physical pain/discomfort & this may be due to physical immaturity & being ridden. Worth ruling those things out, at any rate.