You wouldn't want the Sponsorblock to be part of the download process, but rather the player. Being crowdsourced, it's not immediate and often gets improved/corrected over time, so a video's least likely to have good Sponsorblock timestamps right after being uploaded (when an automated program would likely be downloading it).
We need a Plex/Jellyfin/etc. metadata provider with the Sponsorblock info included. Could keep the data up to date, even after the videos are downloaded.
That seems like it's more on shitty parenting than something affected by advertising, no?