We already have a timeout of 900s (15m) upstream:

commit cfbf10f8701070fba5d8a58b87d59b907e1d9743
Author: Marcelo Moreira de Mello <mmello>
Date:   Fri Apr 7 20:21:40 2017 -0400

    [satellite] increase timeout of spacewalk-debug to 15minutes
    
    spacewalk-debug usually runs longer than the default 5 minutes timeout.
    
    Fixes: #989
    
    Signed-off-by: Marcelo Moreira de Mello <mmello>
    Signed-off-by: Bryn M. Reeves <bmr>

Unfortunately this did not land until a few months after 3.5 was released:

$ git describe cfbf10f8701070fba5d8a58b87d59b907e1d9743
3.5-46-gcfbf10f8

$ git show 3.5
tag 3.5
Tagger: Bryn M. Reeves <bmr>
Date:   Thu Nov 2 12:56:45 2017 +0000

sos-3.5

commit 44a156f506efa55e70af7d0a3344a5b402119059 (tag: 3.5)
Author: Bryn M. Reeves <bmr>
Date:   Thu Nov 2 12:54:47 2017 +0000

    [sos] bump release to 3.5
    
    Signed-off-by: Bryn M. Reeves <bmr>

So it will be automatically included in 7.6 via the rebase: if there are significant problem reports from customers then we could consider releasing this for 7.5.z: the patch is trivial and already tested in several environments.

(the date on the commit looks misleading - although that's the date that it was first committed, it was rebased a number of times and was not finally merged until March this year).

spacewalk-debug belongs to Satellite5 that is not supported/shipped on RHEL7. Despite customers can still install RHEL7 and upstream spacewalk (unsupported) on top of it, Red Hat support won't be interested in a sosreport containing the spacewalk bits. So there is no dedicated need to have this fixed in RHEL7. (and further more, as Bryn wrote, it will appear in 7.6 either way).