It depends on why they are being flagged as suspended - for any campaign that suspends them for a condition, they should also have a campaign to remove and those may be on different timelines. For example - suspend on opportunity created may last until it is dispositioned as won/lost - you wouldn't want to roll these automatically.
You may create a enw custom field in SFDC which synchs to Marketo that is "Individual is currently emailable" true/false and it can look at unsub, suspend, email invalid, etc.