The verb tense is executed exactly correctly (for just the reason that you say); however,

• "Eat like a pig" typically means "eat a lot," as opposed to "eat in a sloppy fashion." (But it's not wrong to use it the way you did either.)
• You mean "crumbs," not "crumbles."

The verb tense is executed exactly correctly (for just the reason that you say); however,

• "Eat like a pig" might be understood to mean "eat a lot," as opposed to "eat in a sloppy fashion." (But it's not wrong to use it the way you did either.)
• You mean "crumbs," not "crumbles."