U.S. Copyright Law Is A Bit Different
The reason here in the U.S. that no one is minding the DCMA takedown notices is this little thing in Copyright Law called "Fair Use". Whilst in blightyland the addition of a heavy sans-serif font with sarcastic messages might not suffice to alleviate copyright claims, it's sufficient enough across the pond.
Further, attempts to take down clear Fair Use satirical images can have a detrimental effect on the company and/or Axl Rose by means of financial penalties they could face for the improper takedown notices.
Yes, it's sad that fat-shaming is still a thing. Yet, Mr. Rose has been a public figure for most of his life and should expect that shocked fans would take issue with his extraordinary change. At least it's pretty clear he's no longer on heroin.