can you? yes, of course. should you? probably not. will it hurt you? probably not. will it help you to do it and swallow? no one knows because no one has done it consistently and reported back here. it may negate some of the effects of doing it and it may not. my guess is that the benefit would be less, but i have no idea to what degree.
i could do it, but i wouldnt want to. i dont go to any great lengths to cleanse my mouth afterwards. usually these days i just spit a few times afterwards. if it is handy i do like to brush my teeth afterwards sometimes because i feel the plaque is loosened up then. beginners should brush before pulling to stimulate the flow of blood in the tissues. especially brush the tongue before, because that is less the oil has to hold that can be removed by other means.
if what ends up in the oil was going to make you sick, you would have been sick already. sending it down the out-spout may be a viable alternative. i like being able to spit that crap out of my body instead of ingesting it for a second time. there may be some hidden benefit to it, too. i have heard of stranger things.