Nothing will happen; it's stable (It would take quite a lot of force to make it fall; I've never had the slightest problem with it).
It's not the entire weight, though it's probably about 80% (20% on the front wheel). And the static load on the engine cover is negligible. The cover must be able to withstand (and has been tested to withstand) a dynamic impact against an obstacle in the rare event of contact during a technical section (this has happened to me several times when riding through more challenging technical sections on my all three ebikes).
I've also improved the stand with zip ties (6 or 7 pieces, I'm not at the stand right now, so I don't know the exact number):
ZabezpeÄŤte, svazujte, upevnÄ›te - nikdy to nebylo snadnÄ›jšĂ, protoĹľe buÄŹ hledáte vhodnĂ˝ kabel nebo elastickĂ˝ popruh. Náš popruh kombinuje vĂ˝hody obou systĂ©mĹŻ - bez jejich nevĂ˝hod. Je pouĹľitelnĂ˝ jednou
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This will create a better contact surface. It provides better grip and is gentler on motor cover.