So in order to claim signature bounty, we're forced to register on Telegram, which correct me if i'm wrong, also requires to provide a phone number and a bunch of other info of the owner. If that's the truth, why on earth is this necessary? It's not like it will prove that my email is not hacked as the telegram account was never associated with my email or bitcointalk account anyway. It's just seems like a silly way to grab some private info from the promoters.

Having to register for Telegram is an additional security measure and is just used to process your claim request. The team is not doing anything with your phone number or any other information.
Providing newly created Telegram account doesn't add any security as my bitcointalk account and email address was never associated with Telegram. All you doing here is trying to take more private information. In addition to that, it is even possible to provide a temporary phone number when registering to Telegram. You're just making claiming process unnecessary complicated.
I agree that the claim process is not the most simple way, but the team has chosen this route because they felt it was the best way to go. If the team really wanted your private information, they could have implemented KYC during the fundraiser.
Ideally, everything should be done automatically, but since there was no blockchain nor web wallet during the fundraiser, there was no real way to do distribute the BOScoins automatically.