Your *friend* was probably banned for participating in an on-forum altcoin giveaway (given the ban duration and the timing of this thread). As you may have guessed, the ban is temporary. He should wait it out since using any account he owns for anything except appealing his ban would be considered ban evasion.
As others have stated, the Trust system is a separate thing.
what is the intent of giveaway what can be explained?
I'm not quite sure what you are asking me about, but read through this:
https://bitcointalk.org/index.php?topic=434310.0. Someone ran a giveaway that required you to post on a thread,
you your *friend* participated in said giveaway, I found the giveaway, trashed it, banned the OP and everyone who participated in it.