If you really want to be picky, you could argue that in Sleeping Giant he is also playing a voice of the chords, occasionally..and in IM and ATC he is playing 5th chords and not single notes...
But I am sure you get it...he is very lazy in all the arrangements there, that's quite clear.
No harmony, no melodic support, no counterpoint...just basic chugga-chugga*!
Add this to the fact that the keys are low (and all the harmony is left to them!) and the bass drum is doubling most of the chuggas...
IMHO it's the worst JP ever heard, speaking about the "background" work...
Just my opinion of course, but the "chuggas" are a fact...
First of all, you had "chuggas" in the Take the Time intro or the Metropolis verse, you had them in The Mirror and Scarred. They're all over the classic material. Something like the Learning to Live verse isn't really all that different from what he does in Sleeping Giant - some rhythm with the occasional move to the chords thrown in. Caught in a Web had a bit of a riff coupled with a lot of chugging, like the first verse of The Alien has. So in general, that's just JP being JP. It's what defines DT's sound to a significant degree.
Then it's really arrogant and silly to call him "very lazy". The silliness becomes obvious when you realize that for all these songs except Answering the Call, he's playing something completely different for the other verse. If he was just lazy, why did he even bother to think of other things to play there instead of just repeating himself? Because it's not laziness, it's a very simple artistic choice. Clearly, JP wanted the basic rhythm there to be more emphasized and heavier than it would be if you only had bass and drums playing it. It's a perfectly valid arrangement choice.
And then you basically ignore the rest that is going on, because in most cases, the guitar part isn't the main attraction and it's not even the 2nd most important thing (that's Jordan's role - and I disagree that the keys are too quiet). And so you often have Jordan doing what you want JP to be doing - providing melody support or counterpoint. And that's really enough - the focus is meant to be on the vocals, you have odd rhythm subdivisions underneath (The Alien is in 17, Answering the Call in 13, Invisible Monster in 7, Sleeping Giant in 9, Awaken the Master has groupings of 5 against 4/4...) and Jordan is already embellishing the harmonies with additional lines - there is barely any room for the guitar to be doing more without cluttering things up.
And then there's the harmonic dimension. As you said, JP is adding chord notes to his part in SG under the vocals, so it's more than just mere "chugga chugga", it is in fact some harmonic support (and of course it's an interesting pattern in 9 to start with and it comes with an added run as a tag). But the guitar remaining on the same note is also not necessarily a sign of laziness but can also be a deliberate compositional tool - it provides a pedal point which gives the chords on top their character. And this is indeed what happens here in most cases. In fact, I find the harmonic work Jordan adds on top of these sections in Awaken the Master and View (the intro) very creative and greatly successful. And the impact of having a pedal point is even emphasized further when you have JP actually changing the notes he's playing throughout the first verse of Awaken the Master, showing very clearly how different the section comes across when he *does* move away from the pedal tone and follows the chords instead. And again, this type of "less is more" restraint is clearly a deliberate choice so you can even have the feel of advancement when he does change things up harmonically later.
So I'd say what's actually lazy is this context-free generalizing and denigrating of perfectly valid, clearly carefully considered and both rhythmically and harmonically varied backing parts as somehow uniform "chuggas".