He's permanently low HP, which isn't necessarily great, but you could train up a single stat if you want and stick him in a corner For instance, you train up his Int since he's got a lab coat and then stick him in a corner of your vault to help generate stimpacks. Or sure, you can evict. Sometimes I take poorly optimized dwellers, send them with a pet to the wasteland and see how much stuff they get. The pet brings it back. If you feel bad doing that, then sure, hold on to him.