Unless there is a specific local regulatory requirement (eg FDA) / industry best practice etc restriction on the idea, it usually comes back to risk assessment.
More specifically, can you validate that the line after use for feed material is then appropriate for food grade product ?
Do you even know how to validate such a requirement ?
As a partially comparable example you might consider the control requirements for allergenic/non-allergenic materials running on the same line. This has only one variable involved, albeit a potent one.
I have occasionally encountered related scenarios regarding re-use of treated/analysed wastewater. Sooo tempting to recycle but equally so potentially contentious. I audited one factory which had just had a strike after it was discovered that the highly treated effluent wastewater was subsequently being officially used for the in-house vegetable garden. And eventually served back at lunchtime. The perfect closed system perhaps. Rapidly discontinued after the consumer backlash.
Offhand, yr idea sounds to me like a simple "best avoided" zigzag unless you have a rock-solid scientific backup/justification.
Rgds / Charles.C