I agree. I mean, in an ideal world, I think it would be great for people to wait for a divorce to be completed before dating again, but practically, once you tell someone it's over and file for divorce, I see no evil in dating. Some divorces drag on and on and on (I;m looking at you, Angie & brad). It's fine to get on with your life.
So, this is how I understand the timeline, based on what others have said (please correct if I have details wrong): Harrow finished filming in August/September 2020. Ioan told Alice he was divorcing her on January 1st 2021 and filed on March 1st 2021. Apparently, he hasn't been to Australia for a year and Bianca has been in australia all this time (until going to france a few weeks ago). So, the argument is, what are the chances that there was no relationship betwn Ioan and Bianca until he left Australia, filed for divorce, then got to know her solely over Skype and invited her to stay with him in France for 2 months based on lovely cross-planet Skype conversations? The timeline points to them hooking up, or at very least getting emotionally entangled, in 2020... well before he told Alice he was done.