Is the implication here that only untalented people would ever put up with working in an office?

Not directly. The Dead Sea Effect says "those who can find an acceptable new job the fastest will leave first". That usually means the super-stars and more-talented, but the residue behind all that evaporation isn't all salt. Some people, even the most employable, will stick around, while their benefit/cost/risk/tolerance kind of equation still allows it.

For some people, RTO doesn't hit their cost and tolerance all that hard. The more unsuitable a person's home environment is for work and how easy their commute is, that'll greatly affect forced RTO acceptance and the Dead Sea Effect.