Just wanted to update my OP here. After doing more research outside of Thinkpads (amazed that more people were not complaining of this....as I'm sure there must be a decent share of older Thinkpad users still wanting to run Windows 10), I found what looks like a solution.
Under Advanced mouse settings > Touchpad, there is a section called "Smart Check Settings."
Under here is an option called PalmCheck with the following description:
"The PalmCheck™ feature guards against operating the TouchPad with accidental contact. PalmCheck allows the TouchPad to recognize when your palm is resting on it or brushing its surface while you are typing. This will help to prevent unwanted pointer movement or clicks.
If the TouchPad exhibits undesired pointer movement or clicks, increase the PalmCheck setting by moving the slider to the right toward Maximum. If the TouchPad misses intended motions or taps, decrease the PalmCheck setting by moving the slider to the left toward Minimum. You are more likely to experience missed motions or taps if the slider is in the red zone."
I didn't think this was really an accurate description of what was happening to me, but there is also a checkbox on that screen to disable (enabled by default) an option called "Prioritize for TrackPoint and keyboard input" with the following description:
"Prioritizing for TrackPoint and keyboard input will temporarily ignore contact on the touchpad for a short time following input on either the TrackPoint or keyboard.
Smart Check Settings can help reduce unwanted touchpad behavior. See each setting for more detail."
This sounded exactly like what was happening to me...the touchpad becoming disabled for a short time, bit I didn't think it was necessarily due to using the keyboard (I rarely use TrackPoint). I disabled this option and over the course of at least 2-3 hours of use over several computing sessions have not experienced the issue again.
I don't know if this 100% solved it, but so far all signs point to yes as I would have experienced this issue at least 3 or 4 times during the same usage period.
I'm not sure if this feature was new with the latest drivers, enabled by default, or simply more sensitive but it didn't seem to affect Windows 7 build on this system.
Hope this helps someone else!