Yes, fully agreed.
Please do not misunderstand, my intention for posting the link above was not a recommendation for using a shotgun microphone for such an application, and certainly not intended to imply that using a stereo shotgun for solo piano is in anyway a prefered method, but rather was meant only to serve as example of good sound quality despite imperfect coincidence of the capsules along the X-axis, with the bi-directional Side capsule placed immediately behind the Mid capsule. It is a continuation of the previous discussion about this type of extremely flexible/compact stereo microphone arrangement working acceptably or not.
If one were limited to using only such a in-line arranged M/S microphone for solo piano in a good hall, closer placement using an omni Mid rather than a interference-tube supercardioid Mid would be advisable. If not limited to using such a microphone, alternate stereo microphone arrangements such as what you've posted immediately above will generally be prefered. However, the converse is not true- in situations where a relatively highly-directional stereo microphone is appropriate, the substitution of omnis is unlikely to work well.