"Prison" (carceral punishment) does not encompass all possible restrictions on personal freedom and movement. Even in systems with carceral punishment, other restrictions on freedom and movement are used for some situations, that do not involve incarceration.
It does not help your cause to adopt a motto that espouses a more extreme position than you actually hold and both your supporters and detractors will feel betrayed when they learn your position is actually more moderate.
So what? You say "DEI" or "woke" and people assume you mean racism against white people. You say "toxic masculinity" or "feminism" and people assume you hate all men. "Pro choice" means you choose to murder babies. Transgender people are pedophiles and fetishists. Immigration is invasion. Atheists are incapable of morality. Opposition to Israeli Zionism is antisemitism. Any economic system besides free market capitalism is socialism, all socialism is communism and all communism leads to the death camps. Democracy is the worst system except for all of the others. By the way did you the Nazis were socialist, and BLM was a violent Marxist army that burned entire cities to the ground?
Most people (especially Americans) have been indoctrinated by society to be unable to interpret any radical or leftist concept in any but the most extreme bad faith way possible, so they don't have to take it seriously. Their minds are protected by a cloud of thought-terminating cliches. Despite this, one doesn't let the opposition control one's language or police one's tone, because that just leads to one's own argument being co-opted and undermined.
The position being described here begins with "abolish the prisons," it just doesn't end with that. But that isn't reform, and if one called it "reform" just to be civil, no one would even bother to listen. Even getting people to consider the nature of the systems they live within and benefit from enough to say "abolish the prisons? That's crazy talk" is getting them to examine their biases more deeply than they probably have in their entire lives.
That is true, there is a concerted effort to control the narrative and define terms that are left vague with the most unfavorable or extreme interpretation. This is possible is because these terms are left so open to interpretation, however the vagueness is not an accident rather it is fully intentional.
The real reason that slogans like "defund the police" and "abolish prisons" are so vaguely defined is because America's two-party system demands "big tent" politics. Both parties need slogans that will unite both extremists and moderates on their side of the political spectrum. The fact that "prison abolishment" can be interpreted as both "fundamental reform" and "all prisoners go free" is a feature, not a bug.
Most politicians will actively avoid giving a solid definition to these slogans, because they know that when they do they will a lose voters. So be aware that adopting vague slogans is to your own detriment too, because the people you think support your position may not actually share your interpretation.