First: it's likely you mistook the decision - it's not a reviewer's comment, it's the editor's comments, and they are desk rejecting your manuscript. In this case it is decently common for the editor to suggest another journal (especially if it's published by the same publisher). I would not find it a red flag if they did - it is after all only a suggestion which you are under no obligation to follow.
You write that the editor recommended a journal on Beall's list, but remember that Beall's list is not gospel, especially since it is now defunct and not being updated. There is a real chance that the editor does not consider the journal predatory, or even that the journal isn't predatory in the first place. The editor is very unlikely to have anything to gain if you submit to a predatory journal either - the other journal might not even know your paper has been referred.
If you do not want to submit to that journal (especially since it is open access with an APC), simply ignore the editor's suggestion and submit your paper elsewhere.
I found that a member of the editorial board of the SCIE journal, is also in the editorial board of the Beall's list journal.
This doesn't mean anything. It is conceivable that a reputable academic will elect to serve on the editorial board of a "predatory" journal (inverted commas because what is predatory isn't well-defined). Or it could be that the predatory journal is simply listing the editor's name without their consent. Either way, this doesn't say anything about the SCIE journal.
Even if this editorial board member is the editor who rejected your paper, it's still possible they are be acting with completely benign intentions (if your colleague told you their paper's been rejected from X journal and you knew of journal Y which would consider it, would you suggest it?). Bear in mind that if they are editorial board members of both journal they would have a pretty good idea of the standards of the other journal, and that your paper meets those standards.
I would take the fact that the journal is indexed by the SCIE as a very strong sign that the journal is reputable (anyone who's ever tried to get a new journal into the SCIE will be able to vouch for how difficult this can be).