I've generally regarded his motivations as "be supine" and "pander to the right", whatever his role. His position on "papers please" type issues is mixed, saying one thing and doing another. I can't tell if that's because of his own personality, or because of ongoing prejudice in the British system and in the Conservative party, requiring him to not be too challenging. The way he was pushed out of the Chancellor position by Dominic Cummings sounded awful; I'm surprised he accepted another job under the present governent.
He was Home Secretary before being Chancellor, and in that role opted to keep up the Hostile Environment policies and Deport First, Appeal Later policies.
I mention those two, because they are indicative of a "papers please" type of culture.
The former requires every minor landlord to perform a "right to rent" check on every tenant or lodger they suspect to be not British, or face a large fine. Inevitably leading to landlords choosing not to rent to non-British people to avoid the hassle and risk of getting it wrong, an increase in homelessness among people without the right papers to prove they're allowed to pay for a home, and an increase in abusive housing relationships.
The latter ensure that illegal actions by the Home Office go unchallenged despite statistics showing the Home Office often acts unlawfully and often loses in court. It's very difficult for a person to conduct an appeal after they're removed from their own documents at home, legal support, income, friends, and other resources; this is also borne out in statistics: No appeal lodged in this way has succeeded, which stands in stark contrast to appeals lodged in country.
(The UK Supreme Court just ruled this policy unlawful. I expect the Home Office will try to continue the policy anyway.)
Point is, Javid said he was going to address injustices in the immigration department when he became Home Secretary, and then he didn't.