yes, no doubt, it can just mean food in general.
also possibly the sense of 'main course', I'd imagine.

I mean, I'm joking, I wouldn't put that 'soya' line in, unless I was really really desperate for a cheap laugh on a particularly disastrous night.

It's more, I suppose, that the 'meat' line can risk rupturing a mood: melancholy and meat aren't conventional bedfellows. Quite a few performers of this song, have a line ending in 'feast', half-rhyming with meat, I notice.

A similar example might be the line "Oh cock oh cock, oh gentle cockerel", in the song 'the grey cock'. I wouldn't think of altering that line either, but you'd have to be pretty naive not to imagine that it might in the wrong circumstances provoke a snigger or two. The sexual implication is a part of the song, but it's tricky to handle: you want it to stay an implication, preserve the spooky, sombre elements of the song, not descend into Carry On-style nob joke humour.