why you can't make a choice "not to comment" for creator giveaway

It is hard to understand what you are saying, but from looking at your giveaways it looks like you want the ability to disable comments on the giveaways you create.

I personally do not think that would be a good feature and doubt that it would be added to the site. Also, support will not let you choose a new winner if you say not to comment and the person that won left a comment. You can choose to not send the game if you want, but the winner can leave a "not received" mark on your account. I am not sure, but it may be possible to receive a suspension for not sending the game for that reason as well.

What is the problem with the comments? They are the only option on Steamgift itself to contact the GA creator. If you don't like to see all of the thank you comments you could write in the GA description that people should not thank you.

he only wants bots to join his giveaways

I'm just leaving a comment here...

"only support members or winner can comment in my giveaway" - why not, its not so bad idea 🐼