How come my opponents Red-Eyes Slash dragon was able to negate my guardian statue's effect? I thought RES was only able to negate effects that target?
Guardian Statue's effect targets. It's identical to Golem Sentry aside from having lower stats. It's a bad card that hasn't been reprinted in well over a decade, and thus doesn't use the current wording style.
The mind-boggling thing is that we got Guardian Statue in the TCG the set after we got Golem Sentry, making it completely pointless.
If you want a non-targeting option, you'll have to wait until Konami gives you Flip Flop Frog.
According to my knowledge, you're right.
Guardian Statue's effect do not target, so RESD should not be able to negate it.
May be that was a bug?