Well (he said, putting on his crotchety nitpicker hat), I wouldn't call it a lambic unless it was a braggot (lambic being a beer style). Spontaneously fermented is a perfectly good descriptor all on its own, with a long history of use in various fermented beverages that aren't lambic. Including tej, which is a spontaneously fermented mead flavoured with gesho (Rhamnus prinoides).
Yes, it can work. I think you'd want to start with a lower gravity (say, <1.070) to encourage yeast health, then add more honey later if you want a stronger mead. You might consider boiling some hops and a bit of honey in a small amount of water to take advantage of hops' antibacterial properties.
EDIT: That last suggestion stems both from the use of hops in lambics and the fact that gesho serves a similar antimicrobial purpose in tej. You could of course try making tej itself if you can source gesho, but I haven't looked into it so I have no idea what availability is like.