On the one hand, yes, this is both stupid and really dickish behaviour from Ubisoft. On the other hand…
This should be illegal.
No. Full stop. no. No one should be compelled to continue selling something they don’t want to sell anymore. If it has social value, it should be reproduced and superseded by something owned by society as a whole. The seller shouldn’t, under any circumstances, have the right to disable the things you bought outright from them, but that’s about it.
We have channels we can use to access things that are no longer supported or sold by the developer (and selling something implies – and should imply – support from the developers). It’s absolutely messed up that those channels are themselves illegal, but believing that you should be able to compel someone else to do what you want, against their will, just because you want them to do it is just an authoritarian hissy fit.