This is pretty simple, you can create a watchdog trigger campaign that listens for the change data value activity on the Person Status field (use "Data Value Changes" trigger) with new value constraint set to the "MQL" / "Marketing Qualified" values (set the exact values in the trigger constraint). Use "Member of Engagement Program" filter with "Engagement Program Cadence" constraint set to the "Normal" value to filter-in only the people who're currently receiving the content from the EP.

In the campaign flow, you'd want to use the "Change Engagement Program Cadence" flow step to update the EP's cadence for the qualifying people to the "Paused" state.

Alternatively, you can also set this as a batch campaign that runs periodically (ideally, every time before the nurture emails are sent) to remove people whose "Person Status" value has changed to MQL/Marketing Qualified values (use "Data Value Changed" filter) in the AND configuration with "Member of Engagement Program" filter with "Engagement Program Cadence" constraint set to the "Normal" value to filter-in only the people who're currently receiving the content from the EP. The campaign flow shall remain same as the trigger campaign.
FYR, trigger campaigns process qualifying people through the campaign flow step in real-time i.e., as soon as the set trigger activity (in this case the data value change activity) happens, whereas batch campaigns run qualifying people through the flow step when they're scheduled to run/when they're manually ran.
Hope this helps! Let us know if you have any questions.