I can't answer for Veeam, but what I have picked up on is that Veeam don't want to issue workaround/fixes for an issue in a 3rd party product that has now been fixed by the 3rd party.
So, when kb1985 came out, there was no fix from Dell/EMC for the issue.
We now know that DDOS v126.96.36.199 resolves the issue that Veeam issued the fix for, so Veeam can [quite rightly] say "install the Dell/EMC firmware update to resolve the issue".
The issue only affects users running DDOS 6 (lower than v188.8.131.52), according the Dell/EMC ETA 498457 (top Dell/EMC Support Searching: use the Product "Data Domain OS" or "DDOS" rather than your actual Data Domain appliance when searching, and you will find the actual notes and firmware you need).
DDOS 6 is still not ratified by EMC as an "EMC Data Domain Target Code" version yet, so you are getting ahead of the support curve installing it (I went for it based on the level of integration that Veeam has with DDOS 6, and the enhanced performance). So if you are running DDOS 6, then upgrading to the latest release isn't altering your support standing with Dell/EMC.
In fact, all previous releases of DDOS 6 have been deprecated on the Dell/EMC support site, if you try to download them: they link you directly to v184.108.40.206 now.
So, if you are a Data Domain user running DDOS 6, then you really should upgrade to v220.127.116.11 at your earliest opportunity.
This also makes the need for a Veeam workaround fix redundant.
Note: I've read some other Dell/EMC support articles that are referencing v6.1 code, so expect another minor upgrade release for DDOS 6 sometime soon[ish]