You correctly identified the red flag of a place looking for side-gig work that actually hates any sign of side-gig work. So for starters, great job there, you don't want to work for those people. As much as I hate to just recommend "find better recruiters", that does sound like a pretty terrible recruiter. I wouldn't remove the interesting stuff from your resume because a non-technical chump doesn't understand how technology gets tinkered on.