Well the 1 SSH session bit was for dramatic meme-effect lol, you can actually connect back without issue (at least it did for me) so worst case if you weren't working in tmux you'd just have to start dd again
Worst worst case, you'd just end up back where you were probably heading before anyways, KVM/IPMI
Sure, I suppose as long as sshd is up and running in the ramdisk environment (which you mentioned in another comment, along with all other services) you could always reconnect. Very neat and clever!