
I think his reasoning is that if he tells his mum then she will either come with him (and put herself in danger) or she will spill the beans when pressured. Also some people don’t tell loved ones secrets because they don’t want to put them in a position to lie to others and undermine their integrity. I personally think she would spill the beans if pressured and he knows that. Also I doubt his phone works rn. It’s probably as dead as a dodo.

He doesn't have to give her any info to let her know he's safe. He could have sent a errand boy with an "I'm safe, don't worry." message before he left the mainland. His mother is freaking out thinking he's missing. There were so many ways to avoid that.
His mother getting "I'm safe" isn't anything to spill.
If the mother told the alpha that she got a note saying that, what would he do with that info exactly?

But does he really have anyone he can trust? Other than this mother, does he have anyone he can ask for help? You said errand boy but who would that be? I’m not saying you’re wrong cause I do think he could have done something even if it’s sending a hand written letter but I do think you’re overestimating the mental capacity a scared and alone pregnant male omega can make when they feel their baby’s and their own lives are threatened. Even if he’s making the wrong choices here and there, he’s pregnant and probably in his second trimester and confused and scared and hormonal. I don’t think you can blame him in that situation.
He left and made his mother worry???
Why not leave, tell your mother you're safe and tell her not to speak to the young master??
Letting your mother worry is insane