Hey that wasn't very nice to the loach. Hes trying to tell you what to do to help the situation, but instead you are getting reactive, instead of taking a step back and considering what was said to help you.
1, the pleco needs supplemental food, they have HUGE appetites and need to be provided their own food.
2, common plecos need a huge tank, over 200 gallons. They get huge and have a huge bioload for tanks too small.
3, common plecos don't eat your plants. The swords would become frayed and damaged from a huge pleco grazing on the leaves. It's just collateral damage to your plants, not deliberately being eaten. Anyone with pleco experience can tell you that overtime they can wear out the leaves of plants with their teeth.
4, common plecos need more meaty foods in their diets as they grow large, yours is at this size.