The complaints about "slope" that have gone to Offcom were made by Somi Guha, not right-wing politicians, and the complaint about the n-word was raised by the Mirror, the only left-wing tabloid, whereas Clarkson has used his column in Murdoch-run The Sun to defend himself and he has been supported by right-wing politician and Prime Minister of the UK, David Cameron.
Anyway, the "witch hunt" claims were made when it was discovered that a swathe of BBC presenters from the 1970s were guilty of or suspected of paedophilia. Of course, the Catholic Church also claimed to be subject to a "witch hunt" when similar revelations of its own actions came to light, but the cry of "witch hunt" was treated with the scorn it deserved.
I see it as more nuanced than this. I think that there demonstrably is a good deal of anti-BBC sentiment among many (most?) other areas of the media - the basis of which has a fair amount of justification (the BBC clearly enjoys an anticompetitive advantage in the TV, radio, online and general-news-dissemination markets owing to matters of broadcasting licences/access and the compulsory public licence fee). There is therefore a clear agenda among many large competitors to the BBC - of whom Sky and the Mail are the most vociferous and hardline - to denigrate the BBC at any opportunity.
However........ I think that this factor is also often used as a smokescreen by the BBC, its staff/employees/contractors and its apologists:
"Oh well, they would say that wouldn't they? They hate the BBC and want to see it destroyed at all costs." Sometimes this counterargument is fair and warranted Often it is not. In my opinion, in this Clarkson matter, it is not warranted: the criticism of Clarkson - and, by extension, the BBC itself - is justified and appropriate.
I will, once more, state my personal position on this issue. I think that there is now more than sufficient evidence for any reasonable person (or corporation, or regulator....) to conclude that Clarkson (and Top Gear as a programme) has an inappropriate and unacceptable attitude to racial, gender, sexuality and nationality issues. This is all about a pattern of behaviour, which is a) demonstrable, and b) admitted to -
then laughed off, minimised or excused - by the show's presenters and producers.
In the latest two issues ("Slope-gate" and "Eeeny-Meeny-gate"

) it's now beyond question that Clarkson and the producer both knew exactly what they were doing: deliberately and willfully trying to insert casual racial slurs into the programme. In the "Slope-gate" incident, the insult - remarkably - made it to air in the broadcast edit, despite the producer and presenter knowing full well (as they have admitted) that it was deliberately intended to be a thinly-veiled racial insult. In the n-word incident, I think that the totality of the evidence tends to strongly suggest that the presenter (and probably also the producer(s)) had an original intent to include the word in the broadcast edit, but decided upon filming the segment that it was impossible to say the word in such a way that the racist slur was subliminally conveyed while retaining sufficient deniability of having used it (in other words, Clarkson couldn't manage to mumble the n-word ambiguously enough that they could have their little joke while being able to claim that he had never used the word - or anything even resembling the word).
This is why I think Clarkson, Top Gear and the BBC rightly deserve to be censured and held to account. Schoolboy "humour" is one thing - and it's a staple of the Top Gear philosophy. Evidence (and viewing figures) suggests that a surprisingly large portion of viewers within and outside the UK enjoy this sort of "humour", banter and "blokeishness", so it's an obvious furrow for the show to continue to plough. But when this schoolboy approach extends to a schoolyard treatment of racial, gender, sexuality or nationalism issues, then it crosses the line into becoming entirely unacceptable.