I think, the biggest issue is that Hamas channel was also giving info to Palestinians for important stuff that could save some Palestinians their lifes. That's what Telegram owner said about why not blocking it.

"Telegram has taken an opposite approach. Durov even went as far as making the ridiculous claim that Hamas should be allowed to continue to post on Telegram as it uses the platform to warn Israelis ahead of attacks." - https://www.calcalistech.com/ctechnews/article/sjpbqgkba