This is great feedback. First, to address the concern about scoring..
Each year will be judged on its own and have it's own ranking, but there will also be a total points leaderboard. I thought I made that clear, but maybe not enough.
Regarding categories. These are not set yet so I am looking for input on the exact criteria. For the first few years, "potential" is a good category. I simply listed some as an example to show scoring, not final categories. Input from the community is key here.
To elaborate on your other concerns, someone who puts a young seedling in a pot at age 2, will never get the trunk thickening of one in ground and so would be judged lower on the trunk but more on display.
This comment: "Some more thoughts of mine would potentially having certain categories for certain groups of trees as declared by the poster for that year's judging. IE Growing, developing, and refinement. This could potentially turn each year's judging round have 3 separate judging criteria and complicate things a bit. The benefit would be that seedlings not be judged as a if it were a bonsai" is an interesting idea. Ill dwell on it. I agree it could complicate things but it could also be a way to standardize the categories.
Finally, I think the scoring is a just a fun competetive side element. Its not the goal per se, but being able to get some quantitative feedback each year on their trees and progress is likely to keep people engaged and interested. Of course the real success will be a lot of progression threads over many years, that track a lot of different development with some objective scoring that supports the best way to develop this material/genus.