Not entirely sure, but from your results it would appear so. Try giving the "guards" either a same faction as the owner and assign that faction ID to the door ownership, or script the event (which may give you more leeway in emulating a guard reaction). If you go with the faction option, you may also want to give the guards a "NoLore" so they don't chat about it.
[edit] I just got off of work and I'm a little run-down. Hopefully this makes sense...
Makes perfect sense, I'll give it a shot... Thanks!
[EDIT]Okay, I assigned ownership to one of the two guards, gave them all a common faction, reduced their disposition to 10, and when the lock is picked the do absolutely nothing.
I'm not sure about the best way to script this. I want the PC to have a chance of successful lock picking without starting a fight, with the chance based on things like chameleon spells, sneak skill, and so forth. I'm not certain whether to set it up with the script on the door, a hidden activator, or on the guards.
I was kinda thinking a script something like the "proximity mine" script, only setting a variable that would in turn startcombat instead of casting a spell.
Any suggestions welcome eh?