Paths for a degreeless but established SWE to pivot into AI research

[origamishuttle]

I was initially strongly considering doing WGU's program, but became a bit concerned at the (relatively) lesser emphasis on math, and the lack of options for electives.

I think you have it backward - TESU BACS requirements are less than WGU BSCS. The WGU degree is more challenging and requires more math than TESU. However, if the goal is to learn and prepare for GT OMSCS, then that can be done separately from the degree, so either degree should be suitable. It just depends on which degree program suits your learning style best.