Kris Marszalek, CEO of Crypto.com Chain, explained in another article that the reason for the donation was for charitable purposes, especially that the donation of one BNB is worth many days in school for children, but I think the purpose is manipulation.
At the conference, CZ announced that 1 BNB donated would equate to 66 days of school for a kid supported by Binance Blockchain Charity Foundation. The CEO of Crypto.com Chain said,
The currency (Crypto.com Chain (CRO)) has risen more than 28% in addition to some gains with Binance.
Overall it is good to see some charity acts in the cryptos market.