I don't know, but I do know this. History is not on his side.
There have been 164 RH pitchers, among those who spent most of their careers working after 1900, who have started at least 325 games in the major leagues. (Because that's how far down the list I'd gone before I got tired.)
And this is how tall they were.
Pitcher Height
1 Harang 79
2 Sutcliffe 79
3 Benes 78
4 Carpenter 78
5 Garland 78
6 Gubicza 78
7 Halladay 78
8 Lackey 78
9 Lowe 78
10 Drysdale 77
11 Gross 77
12 Haren 77
13 Jenkins 77
14 Kile 77
15 Krukow 77
16 Lonborg 77
17 Renko 77
18 Sanderson 77
19 Schilling 77
20 Sele 77
21 Torrez 77
22 Brown, K 76
23 Burnett 76
24 Clancy 76
25 Clemens 76
26 Dierker 76
27 Erickson 76
28 Forsch, B 76
29 Garcia, F 76
30 Millwood 76
31 Moore, M 76
32 Perry, G 76
33 Perry, J 76
34 Alexander, D 75
35 Arroyo 75
36 Belcher 75
37 Blyleven 75
38 Bunning 75
39 Candiotti 75
40 Coleman 75
41 Darling 75
42 Darwin 75
43 Derringer 75
44 Ehmke 75
45 Gullickson 75
46 Hershiser 75
47 Lieber 75
48 Morgan 75
49 Morris 75
50 Newsom 75
51 Palmer 75
52 Pappas 75
53 Passeau 75
54 Reuschel 75
55 Rhoden 75
56 Ruthven 75
57 Smoltz 75
58 Stottlemyre, T 75
59 Trachsel 75
60 Welch 75
61 Whitson 75
62 Appier 74
63 Astacio 74
64 Bender 74
65 Buhl 74
66 Burdette 74
67 Burkett 74
68 Dempster 74
69 Eckersley 74
70 Faber 74
71 Gooden 74
72 Hernandez, L 74
73 Hough 74
74 Law 74
75 Loaiza 74
76 Lohse 74
77 Mussina 74
78 Radke 74
79 Rogers 74
80 Ryan 74
81 Stewart, D 74
82 Suppan 74
83 Vance 74
84 Vazquez 74
85 Wakefield 74
86 Warneke 74
87 Willis 74
88 Witt 74
89 Young 74
90 Alexander, P 73
91 Cone 73
92 Dinneen 73
93 Drabek 73
94 Gibson 73
95 Harder 73
96 Hooton 73
97 Hudson 73
98 Jackson, L 73
99 Johnson, W 73
100 Martinez, D 73
101 Mathewson 73
102 Niekro, J 73
103 Niekro, P 73
104 Ruffing 73
105 Saberhagen 73
106 Seaver 73
107 Stottlemyre, M 73
108 Sutton 73
109 Walters 73
110 Wise 73
111 Doak 72
112 Feller 72
113 Friend 72
114 Haines 72
115 Hoyt 72
116 Hudlin 72
117 Hunter 72
118 Jones 72
119 Lemon 72
120 Leonard 72
121 Maddux 72
122 Marichal 72
123 Meadows 72
124 Moore, J 72
125 Orth 72
126 Oswalt 72
127 Quinn 72
128 Roberts 72
129 Slaton 72
130 Stieb 72
131 Tapani 72
132 Tiant 72
133 Uhle 72
134 Williams 72
135 Wynn 72
136 Adams 71
137 Colon 71
138 Coveleski 71
139 Donovan 71
140 Fitzsimmons 71
141 Hadley 71
142 Lyons 71
143 MacFayden 71
144 Martinez, P 71
145 Mays 71
146 McGinnity 71
147 Mullin 71
148 Pascual 71
149 Shawkey 71
150 Trucks 71
151 Ames 70
152 Bridges 70
153 Brown, M 70
154 Dauss 70
155 Dickson 70
156 Fraser, C 70
157 Garver 70
158 Grimes 70
159 Root 70
160 Bush, J 69
161 Chesbro 69
162 Cicotte 69
163 Luque 67
164 Griffith 66
(You'll notice I didn't bother with feet and inches - the distinction between 5-11 and 6-0 shouldn't appear more significant than the distinction between 5-11 and 5-10, or the distinction between 6-0 and 6-1.)
Sometimes it's just ancient conventional wisdom, preserved and passed on for reasons that no longer make sense. And sometimes it's a fundamental condition of the game. We can't always tell. But if Marcus Stroman has a long and successful career as a major league starter, he'll be the first RH pitcher his size to do so since Bullet Joe Bush and Dolf Luque were in their primes. And that was ninety years ago.