yeah if you are clean don't stress too much... they will tell you leather protectant will repel liqiud etc...it will run off your seats..but then what ,its only going to run onto your carpet,..Its all sales pitch far as I'm concerned....the natural oils in conditoners will do much the same as long as they are applied regularly..
So I say why was their liquid on your seats in the first place...
but leather does definately need conditioners to keep it plush, otherwise it dries out and cracks...I've seen lots of lowish km euros with rooted leather cause owners don't condition it...