There is also a bot called estimatesmartfee, those are potentially more dangerous. But joining a telegram channel? Well unless you distrust telegram itself. Oh yeah, you don't actually have to join the channel to view it, as long as you remember the name 
the bot publish messages to the channel. really Telegram bots could be dangerous? I thought that the only problem could be at privacy level (I won't give txids to BitcoinFeesAlert_bot)