I don't think the original wording implies that at all. This is a meaning OP and others are inferring themselves.

"left" is used all the time where no one was purposely doing anything. It doesn't imply that at all.

Was the baby dead? In trying to edit out the word 'rescue' you've left a key detail ambiguous.

You refered to a human as "it", because you didn't want to say "baby" twice but the details didn't include a gender and that sentence structure didn't provide a good way to just refer to the baby once. This is commonly considered pretty dehumanizing choice of pronoun. I'd argue this is much more likely to offend people.

All this to avoid some imagined implied slight by the choice of the phrase "left alone" when there's no whiff that the subject of the verb would be the mother.

There was some eagerness to find offence at a really innocuous headline, but really it's quite a fairly straightforward headline that requires the reader to pretty much try to be offended by a particular reading of what most would consider an innocuous phrase.