The agents must be looking for reasons to deny entry rather than reasons to admit, since that's what the law (e.g. [1]) has always required them to do.
If you come in with a tourist visa, the explicit legal presumption (opposite to presumption of innocence in criminal law) is that you're not fulfilling the conditions of the visa and actually intend to immigrate or work in USA, and the job given to the immigration officer is to interview you until (and if!) they become convinced that you really do meet the conditions - and if they aren't sure one way or another, then it's their duty to deny entry. It's not a new change coming in with Trump, it's that how USA immigration (sadly) works by design.
(b) Every alien 10/ (other than a nonimmigrant described in subparagraph (L) or (V) of section 101(a)(15), and other than a nonimmigrant described in any provision of section 101(a)(15)(H)(i) except subclause (b1) of such section) shall be presumed to be an immigrant until he establishes to the satisfaction of the consular officer, at the time of application for a visa, and the immigration officers, at the time of application for admission, that he is entitled to a nonimmigrant status under section 101(a)(15) .
I think there is a slight misunderstanding in the turn of phrase used by the lawyer and repeated by me. I understand what you're referring to, but the idea of "looking for a reason to deny" is more meant they're going beyond their stated and written duty and creating reasons to deny entry after establishing they have a valid permit for entry with no other reason. It's not that they are just doing their job, it seems some agents are inventing problems or refusing to accept some conditions as OK once properly vetted. It's the idea behind looking for a problem, trying to provoke an issue
If you come in with a tourist visa, the explicit legal presumption (opposite to presumption of innocence in criminal law) is that you're not fulfilling the conditions of the visa and actually intend to immigrate or work in USA, and the job given to the immigration officer is to interview you until (and if!) they become convinced that you really do meet the conditions - and if they aren't sure one way or another, then it's their duty to deny entry. It's not a new change coming in with Trump, it's that how USA immigration (sadly) works by design.
[1] from https://www.uscis.gov/ilink/docView/SLB/HTML/SLB/0-0-0-1/0-0... -
(b) Every alien 10/ (other than a nonimmigrant described in subparagraph (L) or (V) of section 101(a)(15), and other than a nonimmigrant described in any provision of section 101(a)(15)(H)(i) except subclause (b1) of such section) shall be presumed to be an immigrant until he establishes to the satisfaction of the consular officer, at the time of application for a visa, and the immigration officers, at the time of application for admission, that he is entitled to a nonimmigrant status under section 101(a)(15) .