The BBC are very selective in how they hire and fire. Baker's tweet wasn't the cleverest thing he's ever done but I reckon they were quick to sack him because he's got a lucrative contract with them and they were waiting for an excuse.
Now though some "anonymous" person has complained to the police and they are investigating whether or not it was racially motivated. A witch hunt of the highest order.
Meanwhile at the BBC many people have complained that environmentalist Chris Packham has been using BBC programs to further his own agenda and activism. There's even a petition on change.org that's attracted 140000 signatures to sack him. The BBC have completely ignored it, no comment and haven't really reported it.
So Baker is sacked for one daft bad joke whilst Packham is still employed.
That's how daft it is.