IMHO there is a fundamental difference between what was said by Brand and Ross and what Clarkson said.
Brand and Ross aimed an offensive set of remarks towards a person who was not involved in the relationship between Brand and Andrew Sach's granddaughter. Andrew Sachs, an older personality who was not in the public eye and who had no ready access to the media was not able to respond to the remarks which should not have been aired on BBc radio. I accept that Ross made a proper apology, but punishment for atrocious judgement and extreme bad taste had to follow. Brand appeared to apologise but still it appears that he still thought that his comments were funny and, as I understand it, still makes jokes about what he did. Result, greater punishment.
As for Clarkson, as I have already pointed out, GB is a senior politician, with numerous professional spin doctors at his beck and call and is well able to make public comment if he so wishes. He is Scottish, he is monocular and his idiocy [stupidity] has to be tested in the public forum of an election. Comedians have been making similar jokes for a number of years, before he entered Number 10 as permanent occupant. I really cannot see why Clarkson is being pilloried. As I recall, Rowan Atkinson spoke about the dangers of making certain comments unlawful and stifling comment and satire - do we really want to go down that route again?
Humour can aim towards current affairs [not necessarily sexual] and at those who can defend themselves or have gained notoriety. Perhaps it should not be aimed at those who are not in a position to defend themselves or are, perhaps for medical reasons, not in a position to do so. In relation to the latter, I recently saw a well-known '80's-90's comedian make a series of jokes about Baroness Thatcher, referring to her being a 'milk-snatcher' etc. During the last century, they would have gone down a wow but at the time the jokes were told there were other more relevant targets; the former President of the USA, TB, spin doctors, wars about weapons of mass destruction etc. Now, she is, sadly, a widow, has suffered a series of strokes and is obviously unwell. The jokes went down in silence and like a lead balloon and the comedian, somewhat surprised at the silence and lack of laughter said, "Oh, so you don't like those jokes now?" To which a member of the audience yelled out, "No, now pick on something more relevant." The look on his face should have been filmed.