"Not being able to establish a full milk supply is not the reason people have a problem with trans women attempting to breast feed so why is it being bought up as a good reason to object to the practice?"*
Because if a male person never has the body type to be ever able to produce the milk to be able to feed an infant, why has any organisation made this a priority (as one organisation has stated it should be)? But even more importantly, why have medical professionals allowed these male people to not provide enough nutrition to the infants while these infants were supposedly under monitoring and under a medical professionals care, as I have also described above.
There are valid reasons to discuss the lack of production in male people. And your wish to shape the discussion to exclude that lack of production means that people then do not have full information to make their decisions.
And this also goes for the discussion about domperidone. If a woman is prescribed domperidone, are they not being informed of the issues around duration of usage and having the interactions with other drugs discussed. No woman should be shamed for needing assistance that domperidone can give.
However, that should not mean that the issues of male people using that drug and all the other interactions that go with that drug and other drugs that they might be prescribed cannot be discussed and pointed out in posts.
"The reason people object to this is because it is immoral for many reasons other than not having a full milk supply so let's stick to those and leave the supply out of it because it's irrelevant and upsetting."
You, personally, may believe that objections should be only on the moral grounds. However, many people will not agree with you. And those reading will then need to have the full information that we have available to us to understand that there are not just 'moral' objections (which they may not agree with) but direct harms to the infant involved.
"Once you have alienated the women who had troubles breastfeeding themselves with emotive language about starving babies and shown that you're not interested in a factual debate you just want to show that you find trans people disgusting then the stance against it loses a lot of credibility and support, which is desperately needed."
I consider this paragraph is rather contradictory to your stance that this should be presented as being 'immoral'. Can you explain how you would present this issue based on immorality this without conveying any note of disgust about the male people who choose to do this?
How many of the 'factual' posts on this thread have been based on finding 'trans people' disgusting in general?
If you are telling women that we need to have a 'factual' discussion while then saying we cannot discuss all the implications that are known about the issue, isn't this rather contradictory?
By all means criticise poster's for their wording that you find offensive. However, I have seen enough of these discussions to know that your approach, that being to stick to the morality of the topic, gets dismissed all too often by people who fully believe that this is perfectly fine and healthy for the child involved. It also gets many posts deleted by people who feel the discussion is then based on hate.
I really don't believe that your approach of avoiding all discussion about supply and the use of domperidone is at all helpful to explaining why this is an issue.