The criticism which he linked to primarily pointed out that he was speaking well of a company that exists primarily to enable the surveillance state. My reading of the mention of contributions to politicians in the last paragraph was to point out that this company is contributing to people who Lessig almost certainly does not agree with politically.
But Lessig's response is entirely focussed on not being tainted by any contributions.
He seems to get it what the root of the criticism is: " The essence of the criticism is that Palantir is a bad company, or that it has done bad things, or that it has been funded by bad people."
But his response is "I am completely in favor of questions being raised of anyone like me (meaning people trying to push a particular public policy) about whether mentioning a company or their product is done in exchange for money."
No one ever raised this question. It's not a suspicion. I think what we'd like to know from Lessig is:
1. Do you think it's okay to engage in wholesale spying on Americans, as long as it's subject to what you consider the appropriate oversight?
2. If you don't like spying, are you speaking well of Palantir because you don't think they are involved in it, or are you just interested in the one aspect of their technology and not trying to promote the company as a whole?