[Procedural]

> The supporter could ask bank to mail him a receipt from the transfer. And then show this transfer or have it notarized in most extreme case. Thus proofing he made it. We already have solutions for this.

No one will believe the supporter. The receipt may be a fake text he/she made.

[Ekaros]

Those people who don't believe a notarized document are unlikely to believe a blockchain entry either. After all it could be hacked? Or faked?

[Procedural]

> After all it could be hacked? Or faked?

The whole premise of blockchain is that no transaction can be altered. What happened -- happened, unlike someone's text or screenshots on someone's servers on the Internet.

[usrbinbash]

Or the Blorkchain is forked.