I think parents are expected to support their children in one form or another. This might be by staying at home and looking after them or it might be financially.
So, this man is not really supporting his old family financially - and actually means to give them less in future if he is a stay at home Dad to a new baby, meaning he earns nothing, so lays nothing to the old family. And clearly, he doesn't look after the previous children either. So in that scenario, he will be providing neither oractical care nor emotional support.
I would equally judge a mother who moved away leaving her children to live with their father and provided neither practical care nor financial support, and then planned to have another family. You would query how well she might look after the new one, given zero provision for the first one.
The reality is that in the majority of cases, children remain with the woman when a relationship breaks down, or if a child has been conceived where really there was never an actual established relationship in the first place. So women are usually looking after the child anyway. It is more often the men who are not living with the child and so don not do the day-to-day looking after and are expected to provide some financial support.
This man is looking to avoid providing practical and financial support for his first children. This is why he is problematic I to the future. Unfortunately, even when men leave a string of women behind them with children, the new woman, if she has low self esteem, may somehow be deluded into thinking this time things will be different and she will be treated differently...or perhaps does not even follow through a rational ought process to think how this is likely to play out for her, given the background.
What is problematic is this thought amongst those with low self esteem, that a baby, early into a relationship might cement the relationship and mean the man stays. It is the 'allowing' onelself to become pregnant by not consistently using contraception and saying an accident occurred - so not being willing or able to admit to themselves or others that they sort of want a baby, but haven't had a clear discussion about it and made a decision - so the responsibility for the decision is removed by saying it's an accident. Sometimes the woman needs to remove responsibility because the man hasn't said he wants a baby or hasn't agreed to it, so an 'accident' allows her to tell him she is pregnant without being responsible. Sometimes it's about denial to oneself and so being able to tell onelself that nothing irresponsible or 'trapping' has been done. It's like saying you don't realise that irregular and inconsiderate use of contraception is likely to result in pregnancy. And people go along with it - so families agree that X is pregnant because there was a contraceptive failure, or X and Y are having a baby after 6 weeks together because their contraception failed and how lovely to be having a baby. People seem to find it hard to say that such pregnancies are not a good thing and should be avoided if at all possible, rather than seen as the norm.
Some people live chaotic lives and unplanned pregnancy results from that.In some ways that is unavoidable because efforts to help people onto longer term contraception are never highly successful.
Many others become pregnant in a semi-planned way of chosen irresponsible use of contraception and leaving everything to chance, as if it is all beyond their control. Society doesn't seem to be willing to speak out on this and call it irresponsible and a choice that people make and one which doesn't set those children up well for the future.
People, including the OP need to take responsibility for whether their have children or don't. I really hope we won't be seeing a thread in a few weeks from Op which says she has found herself with an 'unplanned' pregnancy.