I've never had an issue, I always wonder if those comments come from people trying to infuse with a non-infusion polyester or vinyl ester. I infuse with mine just as I would infuse with an epoxy and it always works just the same.
I would be cautious with the pump if you were doing a lot of it. For a few infusions, the pump will be fine. Realistically it will just contaminate the oil earlier and break it down, so just do more frequent oil changes and you shouldn't have any issues.