The Secret Service ensure Trump can't reveal things to people just as much as they protect him.
The fact that Secret Service protection for former presidents is an entirely optional service that the protectee is free to decline is enough to prove that this is wrong, and even if it weren't, a little bit of common sense will quickly point out the flaws in that theory. Do the Secret Service agents monitor their protectee's phone or intercept and read everything they write down? Do they suddenly rush in and get uncomfortably close so they can eavesdrop if their protectee is whispering in someone else's ear? Of course not. Their job is to protect VIPs, not to monitor or control them. I would go so far as to speculate that agents are strongly encouraged to avoid listening too closely to what their protectee is saying to other people so as to be seen as more discreet and trustworthy, although that's just my instinct of what the culture of the agency is probably like.
Even if Trump were sentenced to "prison" it would likely end up a form of house arrest. Trump isn't going to go to some random state or federal prison...Allowing a rambling old man who knows more national security information than most people into a prison is ridiculous.
I agree, but nevertheless, this would be impossible with the Secret Service in their current form. Legislation would be needed to either strip convicted felons of their Secret Service protection and let another agency handle the imprisonment or expand the Secret Service's functions to include providing custody of such a prisoner. I don't think anyone who matters was ever seriously suggesting we should just fling Trump into the general population of any given prison and let him fend for himself, which is exactly why the cries of "they want Trump murdered!" are so disingenuous.
This is what Action80 is talking about, if anyone's wondering and doesn't want to click his link. There's no one single case against Powell, there's no mention of this case being considered "frivolous," and I don't really think it's all that big of a deal whether or not Powell ends up being "disciplined" by the Texas Bar at all.