(wasn't me!)
A lot of times people will jump, release the pike, and on your screen the pike will appear through the box. The best way to describe the pike's hitbox is a donut wrapping around the shaft of the pike starting at the midway area (thus why it goes through walls). Pikemen need to maneuver the pike to move that donut down the shaft and feed the donut to the enemy (sometimes your teammates inadvertently). So, with that said, start the pikes animation while coming around a wall is no different than a mauler starting theirs or someone slashing at the corner of a building, it's simply our animations take longer to trigger.
While I do agree stabbing directly through objects is pretty sad in itself, I cannot say I haven't done it unintentionally. There are times as a pikeman you say "Hmm, curving this pike around that corner worked...let's try getting it around this one." only to find that feasibly it wouldn't have worked in a realistic setting and sometimes just ends with you exploiting the wall and it looks really bad on your part. I try to avoid using the over-or-around wall stabs, simply because it induces complaints. It's not a big deal to curve it around walls or through windows or through doors (like the criss-crossing wooden ones that have openings).
What is a big deal is when you start curving it up OVER walls that are higher than your character's height, or start abusing thin object layers that you can stab through i.e. the vines in the cabbage patches or a slit in a wall you otherwise wouldn't be able to put the pike through and replicate the angle of it.
Hope that shines some light on what I think is "legal" and "illegal" when using the pike. Like I said before, I've unintentionally discovered a few glitches with it that I try to avoid but due to game mechanics you can't really control them. It all comes down to what is accepted by the admins and what isn't--and so far that line hasn't been drawn to a T that the community pushing for regulations on these things expect.
