It would be difficult to find two characters more dissimilar than Ampleforth and Parsons. Ampleforth is a highly intelligent intellectual; Parsons is a fool of the first order who believes everything the Party has to say. Yet both end up arrested for thought crime. That two such opposite personalities could end up arrested shows that nobody is safe. Intelligence means nothing. Stupidity and loyalty to Party also mean nothing. The state considers everyone in it a potential enemy. The arrests, in their seeming randomness, are about spreading terror rather than dispensing any kind of justice. They are raw displays of the power of the state to exercise life and death over any subject for any reason.
Ampleforth's intelligence is on display when he speaks to Winston in prison. He uses nuanced words, such as "indiscretion." He also uses dangerous words, such as "definitive" in a society where nothing is ever definitive. He puts the needs of poetry ahead of the dictates of the Party. We can understand how he might end up vaporized:
"These things happen," he began vaguely. "I have been able to recall one instance—a possible instance. It was an indiscretion, undoubtedly. We were producing a definitive edition of the poems of Kipling. I allowed the word ‘God’ to remain at the end of a line. I could not help it!" he added most indignantly, raising his face to look at Winston. "It was impossible to change the line. The rhyme was ‘rod'. Do you realize that there are only twelve rhymes to ‘rod’ in the entire language? For days I had racked my brains. There WAS no other rhyme."
The expression on his face changed. The annoyance passed out of it and for a moment he looked almost pleased. A sort of intellectual warmth, the joy of the pedant who has found out some useless fact, shone through the dirt and scrubby hair.
"Has it ever occurred to you," he said, "that the whole history of English poetry has been determined by the fact that the English language lacks rhymes?"
Parsons, in contrast, seems like the perfect Party member, the epitome of what the Party wants. Earlier on, Winston thinks
Parsons, on the other hand, would never be vaporized.
Of course, Winston is wrong. Anybody can be vaporized. Though Parson has clearly been falsely accused by his young daughter, who reports him for saying "Down with Big Brother" in his sleep, he too is doomed.