vaheguru ji ka khalsa vaheguru ji ki fateh
To help with this question, go back to Guru Nanak Dev Ji's experience with Bhai Lalo. He ate with Bhai Lalo, not because Bhai Lalo was a 'Sikh' or a particular caste, but because he was an honest, humble person with a beautiful soul.
To say that Sikhs should only eat from the hands of other Sikhs is the same as saying Brahmins can only eat from Brahmins. This completely erases the values of Gurbani. True Sikhs do not segregate people based on their religion or their caste or their nationality or any other thing.
What we do is use our Bibek Buddhi (discriminatory intelligence) to keep the company of those people who reflect the values of the Guru i.e. honesty, integrity and humility. It is very naive to assume that all Amritdharis hold these values and therefore we must eat only from Amritdharis. There will be many non-Amritdharis and non-Sikhs who actually live a better 'Sikh' jeevan than Amritdharis do.
Btw, the two quotations you have linked refer to immoral people and those who have dishonoured their Guru. This is not the same as good people or those who are attempting to follow their faith.
Guru Nanak Dev Ji didn't eat with Malik Bhago because his food was a direct consequence of bad actions, not because he was not of the same religion/status as Guru Nanak Dev Ji. It's hard to understand how we have gotten to the stage where we think that Guru Nanak Dev Ji would have said 'I won't eat with you Bhai Lalo because you are not a Gursikh like me.'
These are merely my opinions, on the basis of what Guru Ji has shown me through their ten jeevans and Gurbani. There will be many who disagree, but where I see Guru Ji's values being misrepresented, resulting in our youth being misled, it is necessary to speak.
vaheguru ji ka khalsa vaheguru ji ki fateh