Neutered male 'assuming the position' on spayed female?

[Princess]

Hi all,

Hope someone can reassure me, slightly concerned. My female mc Chloe was sat on an armchair when my male mc Theo came along and they started fighting - nothing unusual there, they have fought over who gets to sit on this chair before! Chloe wasn't really putting much effort into fighting him off, maybe as she had just woke up, then I noticed Theo biting the back of her neck as they do when they mate, and then to my horror, I realised he was on top of her, almost in the mating position. After that they both went off, think I must have startled him.

Theo has been neutered and Chloe has been spayed so no chance of kittens, and I understand Theo wouldn't really be able to do much anyway - if you get my drift! But I still don't like the idea of him trying to have sex with Chloe.

Please excuse my ignorance on this subject, but is that what he's trying to do? Is it normal for a neutered Tom to try?