I'm sure the writers were more or less writing along the lines of louiex's answers, and not really aware of any sort of lesbian negative subtext presented there. I've got her labelled in my head as bi for my own peace of mind, so as far as the Tosh that I write is, that's what she calls herself. I'm not too sure about canon!Tosh. If you take it as a one-time "yeilding to temptation" thing, it is squicky.