yeah, i think it's a bit aggressive to take his bat out of the lineup down 2 in the 7th.
if you want to have aggressive player rest settings, i'd be sure to not have anybody else set to be rested. personally i don't use player rest because they never worked right when i tried them a while back, i just set defensive replacements to a 1 or 2 run lead in the 8th to rest a few guys with better defensive players in their lieu.
the guy isn't going to mash LHP so i'd just use more lax rest setting and rest him in about half of your matchups vs LHP. get a backup COF who hits LHP well and you'll hardly notice he's not in your lineup.