The Bug:

Sculk sensors are not activated when spyglass expands.

Steps to Reproduce:

• Expand the spyglass.
  →  Notice how the sculk sensor does not activate upon doing this.

Additional Information:
Partially fixed in 1.20.1.

Quote from the 20w49a Changelog, "A vibration is anything that causes physical motion". I would definitely consider this as physical motion, as you are physically performing this task. This may be considered as a feature request, however, it would only make sense for this to be considered as a vibration as your character is physically moving.