I still am not sure this is a good idea in line with jdmore’s comments. While there are some places (US, Canada, South Africa, New Zealand etc) on the site with reasonably good coverage of their biodiversity in terms of records (at least stuff that has a reasonable chance of ever getting a research grade species ID), there are many locations where this is not true.
In places like Asia, Africa, South America as site usage grows there are going to be more and more first observations of things that are clearly native, and these should not get auto tagged as introduced as your change would do.