Salla Allahu 'Alayhi wa-Sallam Or 'Alayhi al-Salam?

We're told that the phrase salla Allahu 'alayhi wa-sallam (Allah pray for him and salute him) is to be used specifically of Allah's boss. From an article:

SALLALLAHU ALAYHI WA SALLAM MEANING:

The meaning of Arabic phrase sallallahu alayhi wa sallam (abbreviation SAW) is “May Allah honor him and grant him peace” or “peace and blessings of Allah be upon him”. This term should be used specifically when saying Prophet Muhammad’s name.

For other Prophet Alayhis salaam (AS) or peace be upon him (PBUH) should be said. Sallallahu Alaihi Wasallam (S.A.W) Meaning? - My Islam

If this is so, why in Muslim 155a do we read the following?

Abu Huraira reported that the Messenger of Allah (ﷺ) said:

By Him in Whose hand is my life, the son of Mary (ﷺ) [salla Allahu 'alayhi wa-sallam] will soon descend among you as a just judge. He will break crosses, kill swine and abolish Jizya and the wealth will pour forth to such an extent that no one will accept it.

https://sunnah.com/muslim:155a

The Arabic of the quotation:

"‏ وَالَّذِي نَفْسِي بِيَدِهِ لَيُوشِكَنَّ أَنْ يَنْزِلَ فِيكُمُ ابْنُ مَرْيَمَ صلى الله عليه وسلم حَكَمًا مُقْسِطًا فَيَكْسِرَ الصَّلِيبَ وَيَقْتُلَ الْخِنْزِيرَ وَيَضَعَ الْجِزْيَةَ وَيَفِيضَ الْمَالُ حَتَّى لاَ يَقْبَلَهُ أَحَدٌ ‏"‏ ‏.‏

If Imam Muslim thought fit to use this phrase in reference to Isa, why don't (other) Muslims?

Regarding Isa's abrogating, see:

Isa the Abrogator

On Abrogation and the Relationship between Islamic and Mosaic Law

See also: A Short Note Regarding Jibril