@alexsnapper,
The English tenses can be rather subtle.
1) Let's say you were describing a particular student to an administrator; you might say, "He always interrupts people," when describing his classroom behavior.
2) Now you and the administrator are observing a class in progress. Your attention is drawn to one student in particular and you remark, "He is always interrupting people."
To make it more complicated, either sentence would be understandable in either situation but I believe the preferred use is seen in the provided examples.