If it’s not source-available, then it’s somewhere between source-available and OSS - that license is very aggressively in favor of futo and against the general public.

Just to clarify the scale:

Best: FLOSS (GPL, etc)
Better: FOSS (Apache, etc)
Good: OSS (MIT, etc.)
<–Futo is here
Bad: Source-Available <–or here
Worst: Closed-Source/Proprietary