First, dont expect anything to be done with them for a while. This will come down to the deadline.
Second, no, his rights cant be traded. If they dont sign by the deadline, he will be ineligible to sign with a ML team for the year, and will go back into the draft the following year (and the Nats will get a compensatory pick to make up for not signing him).
But it will get done...just not for a while