I dont mind sweets for DS - but some points I want to make
Firstly I am (currently) overweight. I eat a perfectly healthy, normal diet including regular walking around pushing buggy etc. I was on very serious meds to try to help my lifelong problem of migraine that is so bad I agreed to try the meds for 2 years knowing the major side effect was a lot of weight gain - think stones. Well I gained the weight, the meds didnt work anyway, now I am on another med - side effect weight loss (result!) so hopefully am back on my way to how I was before. But what you said was rude and thoughtless. There are a lot of reasons for being overweight. No this teacher might not be overweight for exactly the same reason I am, I am just making the point if someone saw me they might clock me and go "overweight, eats crap" but really I dont. So you need to rethink your attitude and realise we are not all blessed with remotely decent metabolisms or health or mental states or whatever.
Secondly - sweets in moderation - fine. I dont mind. I give them to DS. I am not overly precious about it. BUT and this is a big but - he has SN. And certain foods, with some colourings and additives are soooooooo bad for him. For all children I know but for him, picture days and days of meltdown, tears, violence, agony, all around. It isnt pretty. So while I let him have sweets I try to give him sweets that arent riddled with loads of shit. Just good old chocolate or whatever. Again - not precious, but this is a proven fact, both medically and by thousands of parents in observation, of NT and SN children.
And lastly, DH, DS and I are veggie. So I would be really annoyed if (when) he eats sweets with gelatin in them at school. Of course I know it is bound to happen. I can write on his forms "no gelatin" til the cows come home but when people are passing out sweets to all the other children, it isnt going to work is it.
Now none of these things are issues to end the world! But you asked if you were BU. And that was my answer.