The article (and possibly the FBI) didn’t explain what was special about these strains. Everyone already has E. coli in their guts. There are particularly nasty strains that can cause sickness, but this bacterium is also extensively used in biotech to propagate and express plasmid DNAs and study as a model organism.
A researcher moving to the US could be bringing strains of interest which would actually benefit US lab research. That’s actually the most likely thing one would do. Yes, you should declare what you’re bringing in and have it scrutinized. But most likely this would help US research advance, and Patel is just grandstanding against what was a blunder made while trying to circumvent bureaucratic red tape (i.e. the import would have been eventually approved if done properly).
Plasmids are still the most economical way to propagate DNA and express proteins at scale. Obviously, just to try new sequences out it is faster to assemble DNA synthetically and with PCR.