Yawn. Old man yells at cloud (literally). So he's taking his little netblock ball and going home because of some failed purity tests: bad or nonexistent PTRs, excessive ICMP, oh my! The gentleman's agreements that held together the early internet and web and the unwritten practices like that are long gone, get with the times, there ain't any going back to how it was. Otherwise, feel free to disconnect entirely if you don't want to deal with the new reality.

I'm going to going out on a limb and guess that all of this traffic that isn't related directly to AWS, but its customers. You can set PTRs for your allocated elastic IPs with a request to support. But then again nobody is going to do it because... it doesn't matter. It may have mattered when you were hosting with a block that you actually truly owned, before the ICANN times, but no more. No one cares. Everything is ephemeral, so why should the reverse matter when things get cycled through addresses multiple times per day? If you're seeing excessive anything, then it's probably time to reach out to the abuse contact published in the whois. Let me help you with that:

   OrgAbuseHandle: AEA8-ARIN
   OrgAbuseName:   Amazon EC2 Abuse
   OrgAbuseEmail:  trustandsafety@support.aws.com
   OrgAbuseRef:    https://rdap.arin.net/registry/entity/AEA8-ARIN

   Comment:        All abuse reports MUST include:
   Comment:        * src IP
   Comment:        * dest IP (your IP)
   Comment:        * dest port
   Comment:        * Accurate date/timestamp and timezone of activity
   Comment:        * Intensity/frequency (short log extracts)
   Comment:        * Your contact details (phone and email) Without these we will be unable to identify the correct owner of the IP address at that point in time.

Use modern features built in to modern versions of common packages and products: rate limiting, redirects, filters, and on and on. If you're just blocking to block to make some sort of statement into the void, you're just hastening that balkanization.