Oh, they'd gone there? Even Emma knew, without looking around in the cobwebs of St John's mind, that he had an abundance of issues; abandonment, self-worth, anger, independence, daddy issues, mommy issues, the list was all but endless really. The trust issues were just by-products of a hard life, and with Charles dealing with so many abuse and neglect cases, he should've been well aware of the dangers in revealing to St John that he'd seen more than St John had told.
"Don't we all? Tabitha does, Rogue does, even your dear friend Julio, he has more than a few. Personally, I like to believe I've worked past mine, but I'm fairly certain there are still a few cracks." It wasn't that some people were just flawlessly well adjusted, most people had their own baggage and issues to carry with them, Emma didn't think she knew a single person that didn't have some kind of issue. "The point is, I can help you, if you want me to, without rooting around in your past."
Which was the point really, Charles gave him assurances and then broke them. Emma just had to work around that, make whatever assurances she could with St John and show him that she would not break them.
"I can teach you to block, I can do it in my diamond form and you have no worry of my telepathy," although she'd be decidedly clinical about it all, "And once your block is in place and stable, we can try a light telepathic touch." Of course there would be limits to his strength based solely on that, but she'd address that when he could show a little more trust in her.