I am tending to agree with your last sentence for sure, as to whether I will feed them or not, I am not sure yet.
I have shot pheasants with soybean in their crop.
BUT when you read up on what is found in crops, it proves birds eat anything.
I have a habit of giving more weight to what university research says, however, I am not naïve and know that many times the "results" are not real but just phantoms that will give the university department or researcher the best shot at more government grant money to further study it.
I'm not saying Universities don't tend to have reputable studies, quite often they are rightly esteemed and do some brilliant research. It's just that in this case the research into the toxicity of soy is done by higher echelons so to speak.

Even Universities look up to other researchers and take their word as final, in many areas.
As for the pheasants eating the soy, I don't know; depends what type of soy it is. Personally I am inclined to suspect that the more ancient, primitive types of soy i.e. those found in Asia are edible to at least some animals and birds, since plants that aren't (even toxic ones) are a decided minority.
But I know we have oilseed-bred cultivars growing feral in Australia, so who knows what type you have there.
It does seem soy is overall low toxicity. In studying up on goitrogens, I came across all sorts of info on plants that affect the thyroid or endocrine system, and many of them are classed as toxic even though we know they're incredibly unlikely to kill anyone without an allergy. It's just that soy has some very specific and unpleasant effects over time as compared to most other toxic fodders.
Chooks4life what is your feeling about feeding meat birds that will only be around for a couple weeks soybeans?
I ask because of when you said this "
But, as mentioned before, everything is toxic in some quantity. That said, soy is not something you have to consume large amounts of to experience the toxic results, and they're insidious, causing reproductive defects, endocrine disorders, and a host of other problems. It's not a case of there being a simple toxin which might make your stomach hurt if you eat too much; it's a whole array of nasty toxins which even in low dosage have long term, even cross-generational effects on multiple organ systems...
I would wonder also about pass over effects to my family, especially organs like the liver and gizzards.
Yes, it doesn't seem too advisable to me to have a long term high-soy diet.
It doesn't seem that a short term low-level consumption would do any serious harm to the average chook or human though, as it appears to be something that takes a while to make its effects felt in low dosage. It is a very common livestock and human food source after all. That said it's not like there aren't many dozens of common diseases both we and our livestock suffer based on diet alone.
If I got flooded in again and had a choice of not feeding my chooks or giving them soy feed I know what I'd choose... The lesser of two evils, lol.
As for what effects could occur to you or your family, it's not something easily guessed at. We have so many endocrine disruptors and toxins in our lives these days, and every individual is different in their reactions. I prefer to avoid all I can, since there's always many unavoidable ones which are doing you and your DNA etc damage anyway.
Best wishes.