Here let me help. The sex parts of the male brain are pretty straight forward. By all research, male brains are 'see target, engage target', and the world is a target rich environment. If you show a man an engorged female nipple, a vagina, a butt, even if they have the control to not get an erection (because they aren't 12 anymore) they will still show multiple signs of arousal when measured with the proper equipment, including micro-erections (your penis almost goes for it). This will happen regardless, as long as you find the form attractive in some way, and there isn't anything to mute the sexual trigger (your mom being present. Disease being present. Immense stress. Etc).
Lesbianism could possibly mute a trigger for an individual, but it isn't a common one. For most men, that is just more targets around, and for men multiple possible women is usually just a heavier trigger. At the end of the day, the golden rule is that for men, if your brain says 'yes that is sexy' your penis will 100% agree. They are on a pretty good link with each other. This is different for women (the sexual part of the brain can find stuff attractive while in their 'mind' they do not. Leading to arousal triggers even in high stress, dangerous, or bad conditions. I'll give you a few guesses while that is an advantage in terms of evolution).
Pretty much, nothing about lesbians would stop men from finding them arousing. You may not find them interesting as people, but personality is a secondary trigger anyway. A nude lesbian is just as sexy as a nude hetero woman, all other things equal.