Yes, but they'll need SEGA's permisssion for that and may be SEGA won't allow it.
SEGA didn't allow Joe Musashi to be added in Streets of Rage 4 back then.
Understandable. But I don't think Roblox games go by the same copyright laws as regular games. I believe Gamefam could pull it off by a technicality if Sega were to allow it.
After all, Sonic Speed Sim once did some sort of promotion with a Friday Night Funkin' Roblox game that was not endorsed by Funkin' Crew given this roblox game was only in likeness and not in name.
And what about other Roblox events Sonic Speed Sim has, like Synth City to promote RB Battles?