Is it true that what was attributed to Imam Ahmad ibn Hanbal, that improving one's prayer when people are watching is not showing off but rather "the blessing of a Muslim upon a Muslim"?

Ibn Muflih mentioned in Al-Furu' that Al-Marwadhi asked Ahmad about a man who enters a mosque and sees people, so he improves his prayer. Is that hypocrisy (riya')? Ahmad replied: "No, that is the blessing of a Muslim upon a Muslim." Ibn Muflih explained this, with Al-Qadi elucidating it as waiting for him and repeating [the prayer] with him, or intending [to do so]. He chose in Al-Nawadir that it is permissible if one intends to be emulated or to avoid being thought ill of. If he experiences slackness after his action, the shortcoming is from him, not from the action itself.