Malware protection plan UNSUPPORTED tag

We use the GuardDuty Malware Protection Plan with tagging but for some objects the tagging returns UNSUPPORTED. Those object are pdf document but with Password Encrypted security. We saw in the documentation that this is the reason fo why they are tagged as UNSUPPORTED.

We would like to know :

• Is it planned to handle those type of documents ?
• Is there another way to scan them anyway ?
• If not how are we supposed to handle this UNSUPPORTED tag ? What is the best practice ?