I don't know if at this point being radical means being authoritarian. Now, it appears that in France, being Socialist (more like being a Socialist supporting the current government), is being at center, even at right. If people have to vote for communists (current communists=/=stalinists) to get social progress now, they'll end up voting for that. I don't think we can talk anymore about extreme left in France, except for a few cases like the more radical parties that score like 0.01% each time (related to stalinism), which is like the KKE in Greece.
Even I have to admit, that KKE guys are morons. How can one even believe that Stalin's policy was the best, you must be brainwashed to speak like that of a policy that consisted into murdering small owners and all political opponents.
This said about being radical, to come back on the question, it's not normal to make an alliance with people that are voting for xenophobia. Instead of having despise for the 1%, they have it on guys who barely have anything.