Don't believe "above" makes any sense in the context of Luke 21:10 onwards; "Before all these things (take place)" corresponds to what will occur in a future time as described in Luke 21:10-11, and what is mentioned in v12 onwards will occur "before" them, or "ahead of (the time when)" them if "before" doesn't quite work for you.
As for the grammatical reason; well, yes; because it's just πρὸ, not πρὸ πάντων (see James 5:12; 1 Pet 4:8). There's a reason why BDAG doesn't cite Luke 21:12 as an example of "above".
Edit:
BDAG works here as a good enough explanation:
πρό prep. w. gen. (Hom.+—S. the lit. s.v. ἀνά, beg.; also Rydbeck 62–77) ‘before’.
② marker of a point of time prior to another point of time, earlier than, before πρὸ τοῦ ἀρίστου before the meal (X., Cyr. 6, 2, 21) Lk 11:38. πρὸ τοῦ βαπτίσματος D 7:4a. πρὸ χειμῶνος 2 Ti 4:21. πρὸ τοῦ πάσχα J 11:55. πρὸ τῆς ἑορτῆς τοῦ πάσχα 13:1. πρὸ τοῦ κατακλυσμοῦ Mt 24:38. πρὸ καταβολῆς κόσμου J 17:24; Eph 1:4; 1 Pt 1:20. πρὸ ἡλίου καὶ σελήνης 2 Cl 14:1 (s. ἥλιος). πρὸ πάντων Col 1:17; cp. πρὸ τούτων πάντων Lk 21:12. πρὸ τῶν αἰώνων (Ps 54:20) 1 Cor 2:7; cp. IEph ins; IMg 6:1. πρὸ χρόνων αἰωνίων 2 Ti 1:9; Tit 1:2. πρὸ παντὸς τοῦ αἰῶνος Jd 25. πρὸ καιροῦ before the proper time or the last times (καιρός 3b; cp. Sir 51:30; Theodor. Prodr. 1, 281 H.) Mt 8:29; 1 Cor 4:5. πρὸ τούτων τῶν ἡμερῶν Ac 5:36; 21:38; Hm 4, 3, 4. πρὸ ἐτῶν 2 Cor 12:2. πρὸ τῆς μεταθέσεως Hb 11:5. Latinizing (on the use of the Rom. calendar among the Gks. s. Hahn 245; EBickerman, Chronology of the Ancient World2, ’80, 47–51; on calculation of a date, 43–44) πρὸ ἐννέα καλανδῶν Σεπτεμβρίων on August twenty-fourth IRo 10:3. πρὸ ἑπτὰ καλανδῶν Μαρτίων on February twenty-third MPol 21 (cp. IPriene 105, 23 πρὸ ἐννέα καλανδῶν Ὀκτωβρίων).—On the expr. πρὸ ἓξ ἡμερῶν τοῦ πάσχα J 12:1 s. ἡμέρα 2c and cp. Am 1:1; 4:7. πρὸ τριῶν ἡμερῶν τοῦ συλληφθῆναι αὐτόν three days before he was arrested MPol 5:2. πρὸ μιᾶς τῶν ἀζύμων one day before the feast of unleavened bread GPt 2:5 (Plut., Lucull. 510 [27, 9] πρὸ μιᾶς νωνῶν Ὀκτωβρίων, Publ. 101 [9, 8]; Appian, Bell. Civ. 2, 115 §479 πρὸ μιᾶς τοῦδε τοῦ βουλευτηρίου). πρὸ μιᾶς (sc. ἡμέρας [Polyaenus 7, 10 and Just., D. 27, 5 πρὸ μιᾶς ἡμέρας]; cp. Lucian, Alex. 46; Dositheus 40, 2; PGM 13, 350) one day before D 7:4b; the day before Hs 6, 5, 3.—Rydbeck 62–77; Mlt-Turner 260.—W. gen. of the personal pron. (PsSol 1:8 τὰ πρὸ αὐτῶν ἔθνη; Just., D. 16, 4 πρὸ αὐτοῦ; PTebt 61b, 384 [118/117 b.c.]) πρὸ ὑμῶν (Lev 18:28) Mt 5:12; cp. Ac 7:4 D. πρὸ ἐμοῦ (1 Macc 15:5) J 5:7; 10:8 (s. also 1 above); Ro 16:7; Gal 1:17 (s. AcPlCor 2:4). Cp. 1 Cl 19:1.—πρὸ τοῦ w. acc. and inf. (En 9:11; TestAbr A 9 p. 87, 10 [Stone p. 22]; ParJer 7:31; Just., D. 92, 3. Cp. B-D-F §403; Rob. 1074f) πρὸ τοῦ ὑμᾶς αἰτῆσαι Mt 6:8. Cp. Lk 2:21; 22:15; J 1:48; 13:19 (here the acc. is missing, but can easily be supplied); 17:5; Ac 23:15; Gal 2:12; 3:23; B 16:7.