Trump said that not because he had some particular insight, but it was just a way to deflect blame, and that's why it was super amplified across the right wing, but lacking any sort of evidence or proof. Also back then there was a strong suggestion that it was bioengineered at Wuhan on purpose to tank the western economies.

Note that he also said covid wasn't a serious thing several times. If that's the case even if there was a lab leak it wasn't a big deal? Note that both of those were to benefit his administration and deflect blame from his admin's response in Feb 2020 to not take covid seriously.