No - pitest has no problems with the use of interfaces, reflection etc.
The sentence you quoted relates to an optional feature that allows the tests that will be run against a mutated class to be limited to those within a certain "distance" (i.e number of method calls) from it.
The feature is little used, but is useful in some very specific circumstances.
Even if you do enable it, it would only cause a problem if the class under test was only referred to within the test by some interface that it implemented (which would be very unusual). The fact that the classes dependencies were declared as interfaces would cause no problems.
The sentence you quoted relates to an optional feature that allows the tests that will be run against a mutated class to be limited to those within a certain "distance" (i.e number of method calls) from it.
The feature is little used, but is useful in some very specific circumstances.
Even if you do enable it, it would only cause a problem if the class under test was only referred to within the test by some interface that it implemented (which would be very unusual). The fact that the classes dependencies were declared as interfaces would cause no problems.